Sqlite3 как открыть базу

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Sqlite3 как открыть базу

Для работы с SQLite разработчики данной СУБД предоставляют консольный клиент sqlite3 . Рассмотрим вкратце, как с ним работать.

Прежде всего нам надо загрузить sqlite3. Для этого перейдем на страницу https://www.sqlite.org/download.html. Название необходимого нам пакета начинается с sqlite-tools . И на странице загрузки мы можем найти версии для Windows, Linux, MacOS:

Загрузим нужную нам версию и распакуем ее.

В распакованной папке мы сможем найти три утилиты, из которых файл с названием sqlite3 и представляет собственно консольную оболочку для работы с бд SQLite. Запустим ее:

Открытие базы данных

Для открытия базы данных необходимо ввести команду .open , после которой указывается путь к базе данных. Например,

В данном случае будет открыта база данных под названием «test.db’, которая находится в той же папке, что и консольная утилита. Если базы данных не существует, то она создается.

Также можно передать абсолютный путь:

После открытия мы сможем работать с этой бд.

Создание таблицы

Для создания таблицы после открытия базы данных необходимо ввести команды CREATE TABLE , после которой указываются название таблицы и спецификация ее столбцов:

В данном случае создается таблица users , в которой два столбца: столбец name , который имеет тип text , и столбец age , который имеет тип integer

Обратите внимание, что команда завершается точкой с запятой. И все команды SQL должны завершаться точкой с запятой, благодаря чему sqlite может идентифицировать, что выполняется sql-команда.

Операции с данными

Для добавления данных применяется команда INSERT INTO . Например, добавим в таблицу users одну строку:

Теперь получим ранее добавленны данные. Для этого используем команду SELECT :

How to install and use SQLite

SQLite is a lightweight Database Management System (DBMS) which allows its users to implement a relational schema and run SQL queries over it, without the need for a standalone database server. This is convenient because the setup is minimal and the database can be easily bundled with application files.

SQlite is portable, which means that you can install it on any computer, even when you do not have Administration privileges. It is also quite interesting for mobile development in platforms such as Android or iOS.

SQLite implements ACID (Atomic, Consistent, Isolated, and Durable) transactions. This makes it possible to rollback all changes made during transactions in the event of a system crash or power loss.

SQLite does not, however, implement the SQL Standard.

For our classes we will be using SQLite3.

Installing SQLite3

All FEUP computers have sqlite3 already installed, so you should not need to carry out this step in those machines. If you want to install it in your personal laptop for home work or study, read on.

Manual Installation (portable)

1. Download the precompiled binaries for sqlite-tools from the website and unzip them to a folder in your computer. Please choose the appropriate file depending on your operating system (Windows, Linux or macOS).
   • For Windows, I recommend you unzip the download into C:\sqlite3 . For other OS’s you should use your home folder, like

Automatic installation

macOS

1. Install HomeBrew
2. Open Terminal
3. Type brew install sqlite3 and press Enter.

Linux (debian-based distros such as Ubuntu and derivatives)

1. Open Terminal emulator
2. Type sudo apt-get update && sudo apt-get install sqlite3 and press Enter.

Installing the Graphical User Interface

We will also be using a GUI (Graphical User Interface) to manipulate our SQLite databases. SQLiteStudio is free and runs on every Operating System. Detailed installation instructions for Windows, Mac and Linux are available here.

MacOS

For macOS you can use homebrew. Just run the following command: brew cask install sqlitestudio .

Linux

For Linux, unzip the installer in the downloads page. Open the Terminal, cd to the Downloads folder and make the installer executable by running the command chmod +x ./InstallSQLiteStudio-3.2.1 . Then run it: ./InstallSQLiteStudio-3.2.1 . The installer should start up.

Starting SQLite

In a FEUP machine

1. Press the Windows Key + R . A small window will pop up.
2. Type cmd.exe and press Enter.
3. A command line window will pop up.
4. Type sqlite3 and press Enter.
5. You will now be in the SQLite3 command line.

In your own computer

To create a database you must first navigate to the folder where sqlite3 is installed. Assuming that you unzipped the downloaded files to C:\sqlite as previously explained, do this:

1. Press the Windows Key + R . A small window will pop up.
2. Type cmd.exe and press Enter.
3. A command line window will pop up.
4. Type C:
5. Type cd C:\sqlite3
6. Type sqlite3.exe and press Enter.
7. You will now be in the SQLite3 command line.

Useful commands

Creating your first database

When you first run sqlite3 , any changes will be saved in memory only. This means that if you close the window, all changes will be lost.

You can see the list of all commands by typing .help :

Executing SQL statements

There are two main ways of running SQL in the prompt; the first is to write code directly, the other is to create a .sql file and read it in the prompt.

Here is a piece of code to get you started:

You should see this result:

Reading from a file

Another, more powerful way is to save the sequence of commands and statements in a text file (say, “helloworld.sql”), thus creating a script that you can run via .read. This works as long as you have the sql file in the same folder as you are running sqlite3:

Saving to a file

In any case, you can later save the SQL statements that you’ve used both to create the database (CREATE TABLE statements) and to populate its tables (INSERT INTO statements). For that, you can use the .schema (for the schema creation statements only) or the .dump` (for both creation and insertion statements) commands:

If you want to save these statements into a file you can later read from (using the .read command as shown above), all you need to do is to use the .output command to redirect any output to a file:

The contents of the “helloworld.sql” file should be the statements listed above.

Keeping the Database state in a file

The state of the database can be maintained persistently in a file, avoiding the need to store SQL statements that can be later read (using .read as shown above). In order to do that, you simply need to add an argument to the sqlite3 application: the name of the database to use.

If the file provided as an argument to sqlite3 does not exist, SQLite will create it automatically. Any changes made in the database are persistently stored in that file, without the need for specific save commands (such as .dump). The following example illustrates the creation and use of a persistent database:

An alternative to using the database file name as an argument to sqlite3 is to use the .open command within SQLite. This still ensures that any changes to the database are automatically stored in the persistent file. Similarly, if no file was provided as an argument to sqlite3 you can use the .save command to save the database to a file. Notice however that this does not trigger automatic saves of any additional changes that are made in the database.

Pragma Statements

The PRAGMA statement is an SQL extension specific to SQLite and used to modify the operation of the SQLite library or to query the SQLite library for internal (non-table) data.

Syntax

A PRAGMA statement is formed by the keyword PRAGMA followed by the actual “pragma” that is being defined. A pragma has a name and can take one argument. The argument may be in parentheses or separated from the pragma name by an equal sign. The two syntaxes yield identical results. In many pragmas, the argument is a Boolean and can be one of: 1/yes/true/on; 0/no/false/off.

PRAGMA foreign_keys

This is a very important pragma, as it may be used to set the enforcement of foreign key constraints.

Consider the following SQL statements, which violate a foreign key constraint:

Since in the current version of SQLite foreign key constraint enforcement is disabled by default, loading these statements from a file, say fk.sql, does not raise any error:

If we turn on foreign key constraint enforcement, we get an error detecting the constraint violation:

SQLite Database: How to Create, Open, Backup & Drop Files

SQLite databases are very lightweight. Unlike other database systems, there is no configuration, installation required to start working on an SQLite Open database.

What you need is the SQLite library which is less than 500KB size. We will jump start working on SQLite databases and tables directly.

In this SQLite tutorial, you will learn how to access SQLite database and use it-

SQLite CREATE Database

Unlike other database management systems, there is no CREATE DATABASE command in SQLite. In this SQLite tutorial, here is how you can create a new database:

• Open the Windows Command Line tool (cmd.exe) from the start, type “cmd” and open it.
• The “cmd” will open in the default user folder, on my machine, it is “C:\Users\MGA”:

• Following is the basic syntax of sqlite3 command to create a database
• This will create a new database with the name “SchoolDB.db”in the same directory where you have copied your .exe file.

If you select SQLite file and navigate to the directory: “c:\sqlite”, you will find the file “SchoolDB.db”is created as the following screen shot:

This will give you the list of databases created, and you should see the new database “SchoolDB.db” listed there:

SQLite CREATE Database in a Specific Location using Open

If you want to learn how to open SQLite file and create the database file in a specific location rather than in the same location where the sqlite3.exe is located, here is how to view SQLite database:

• Navigate manually to the folder where sqlite3.exe is located “C:\sqlite”.

SQLite create a database and populate it with tables from a file

If you have a .SQL file that contains the tables schema and you want to create a new database with the same tables from that file, in the following example, we will explain how to do this.

Example:

In the following example, we will create the sample database. We will use this sample database throughout the SQLite tutorial, with the name “SQLiteTutorialsDB” and populate it with the tables. As following:

• Open a text file and paste the following SQLite commands on it:

The code above will create four tables as following:

• “Departments” table with the following columns:
• “DepartmentId” an integer number indicates the department id, and it is declared as a PRIMARY KEY (explained later in Column Constraints Section).
• “DepartmentName” – a string name for the department, and it doesn’t allow null values using NOT NULL constraint.
• “Students” table with the following columns:
• “StudentId” an integer number, and it is declared as a PRIMARY KEY.
• “StudentName” – the name of the student and it doesn’t allow a null value using NOT NULL constraint.
• “DepartmentId” Integer number that refers to the department Id to the department id column in the departments table.
• “DateOfBirth” The date of birth of the student.
• “Subjects” table with the following columns:
• “SubjectId” an integer number and it is declared as a PRIMARY KEY.
• “SubjectName” a string value and it doesn’t allow null values.
• “Marks” table with the following columns:
• “StudentId” integer indicates a student id.
• “SubjectId” integer indicates a subject Id.
• “Mark” the mark a student gets in a specific subject it is also integer and it does allow null values.

SQLite Backup & Database

To back up a database, you have to open that database first as follows:

• Navigate to “C:\sqlite” folder, then double-click sqlite3.exe to open it.
• Open the database using the following query

SQLite Drop Database

Unlike other Database management systems, there is no DROP DATABASE SQLite command. If you want to drop database SQLite, all you have to do is to delete the database file.

1. Getting Started

The SQLite project provides a simple command-line program named sqlite3 (or sqlite3.exe on Windows) that allows the user to manually enter and execute SQL statements against an SQLite database or against a ZIP archive. This document provides a brief introduction on how to use the sqlite3 program.

Start the sqlite3 program by typing «sqlite3» at the command prompt, optionally followed by the name of the file that holds the SQLite database (or ZIP archive). If the named file does not exist, a new database file with the given name will be created automatically. If no database file is specified on the command-line, a temporary database is created and automatically deleted when the «sqlite3» program exits.

On startup, the sqlite3 program will show a brief banner message then prompt you to enter SQL. Type in SQL statements (terminated by a semicolon), press «Enter» and the SQL will be executed.

For example, to create a new SQLite database named «ex1» with a single table named «tbl1», you might do this:

Terminate the sqlite3 program by typing your system End-Of-File character (usually a Control-D). Use the interrupt character (usually a Control-C) to stop a long-running SQL statement.

Make sure you type a semicolon at the end of each SQL command! The sqlite3 program looks for a semicolon to know when your SQL command is complete. If you omit the semicolon, sqlite3 will give you a continuation prompt and wait for you to enter more text to complete the SQL command. This feature allows you to enter SQL commands that span multiple lines. For example:

2. Double-click Startup On Windows

Windows users can double-click on the sqlite3.exe icon to cause the command-line shell to pop-up a terminal window running SQLite. However, because double-clicking starts the sqlite3.exe without command-line arguments, no database file will have been specified, so SQLite will use a temporary database that is deleted when the session exits. To use a persistent disk file as the database, enter the «.open» command immediately after the terminal window starts up:

The example above causes the database file named «ex1.db» to be opened and used. The «ex1.db» file is created if it does not previously exist. You might want to use a full pathname to ensure that the file is in the directory that you think it is in. Use forward-slashes as the directory separator character. In other words use «c:/work/ex1.db», not «c:\work\ex1.db».

Alternatively, you can create a new database using the default temporary storage, then save that database into a disk file using the «.save» command:

Be careful when using the «.save» command as it will overwrite any preexisting database files having the same name without prompting for confirmation. As with the «.open» command, you might want to use a full pathname with forward-slash directory separators to avoid ambiguity.

3. Special commands to sqlite3 (dot-commands)

Most of the time, sqlite3 just reads lines of input and passes them on to the SQLite library for execution. But input lines that begin with a dot («.») are intercepted and interpreted by the sqlite3 program itself. These «dot commands» are typically used to change the output format of queries, or to execute certain prepackaged query statements. There were originally just a few dot commands, but over the years many new features have accumulated so that today there are over 60.

For a listing of the available dot commands, you can enter «.help» with no arguments. Or enter «.help TOPIC» for detailed information about TOPIC. The list of available dot-commands follows:

4. Rules for «dot-commands», SQL and More

4.1. Line Structure

The CLI’s input is parsed into a sequence consisting of:

• SQL statements;
• dot-commands; or
• CLI comments

SQL statements are free-form, and can be spread across multiple lines, with whitespace or SQL comments embedded anywhere. They are terminated by either a ‘;’ character at the end of an input line, or a ‘/’ character or the word «go» on a line by itself. When not at the end of an input line, the ‘;’ character acts to separate SQL statements. Trailing whitespace is ignored for purposes of termination.

A dot-command has a more restrictive structure:

• It must begin with its «.» at the left margin with no preceding whitespace.
• It must be entirely contained on a single input line.
• It cannot occur in the middle of an ordinary SQL statement. In other words, it cannot occur at a continuation prompt.
• There is no comment syntax for dot-commands.

The CLI also accepts whole-line comments that begin with a ‘#’ character and extend to the end of the line. There can be no with whitespace prior to the ‘#’.

4.2. Dot-command arguments

The arguments passed to dot-commands are parsed from the command tail, per these rules:

1. The trailing newline and any other trailing whitespace is discarded;
2. Whitespace immediately following the dot-command name, or any argument input end bound is discarded;
3. An argument input begins with any non-whitespace character;
4. An argument input ends with a character which depends upon its leading character thusly:
   • for a leading single-quote (‘), a single-quote acts as the end delimiter;
   • for a leading double-quote («), an unescaped double-quote acts as the end delimiter;
   • for any other leading character, the end delimiter is any whitespace; and
   • the command tail end acts as the end delimiter for any argument;
5. Within a double-quoted argument input, a backslash-escaped double-quote is part of the argument rather than its terminating quote;
6. Within a double-quoted argument, traditional C-string literal, backslash escape sequence translation is done; and
7. Argument input delimiters (the bounding quotes or whitespace) are discarded to yield the passed argument.

4.3. Dot-command execution

The dot-commands are interpreted by the sqlite3.exe command-line program, not by SQLite itself. So none of the dot-commands will work as an argument to SQLite interfaces such as sqlite3_prepare() or sqlite3_exec().

5. Changing Output Formats

The sqlite3 program is able to show the results of a query in 14 different output formats:

• ascii
• box
• csv
• column
• html
• insert
• json
• line
• list
• markdown
• quote
• table
• tabs
• tcl

You can use the «.mode» dot command to switch between these output formats. The default output mode is «list». In list mode, each row of a query result is written on one line of output and each column within that row is separated by a specific separator string. The default separator is a pipe symbol («|»). List mode is especially useful when you are going to send the output of a query to another program (such as AWK) for additional processing.

Type «.mode» with no arguments to show the current mode:

Use the «.separator» dot command to change the separator. For example, to change the separator to a comma and a space, you could do this:

The next «.mode» command might reset the «.separator» back to some default value (depending on its arguments). So you will likely need to repeat the «.separator» command whenever you change modes if you want to continue using a non-standard separator.

In «quote» mode, the output is formatted as SQL literals. Strings are enclosed in single-quotes and internal single-quotes are escaped by doubling. Blobs are displayed in hexadecimal blob literal notation (Ex: x’abcd’). Numbers are displayed as ASCII text and NULL values are shown as «NULL». All columns are separated from each other by a comma (or whatever alternative character is selected using «.separator»).

In «line» mode, each column in a row of the database is shown on a line by itself. Each line consists of the column name, an equal sign and the column data. Successive records are separated by a blank line. Here is an example of line mode output:

In column mode, each record is shown on a separate line with the data aligned in columns. For example:

In «column» mode (and also in «box», «table», and «markdown» modes) the width of columns adjusts automatically. But you can override this, providing a speicified width for each column using the «.width» command. The arguments to «.width» are integers which are the number of characters to devote to each column. Negative numbers mean right-justify. Thus:

A width of 0 means the column width is chosen automatically. Unspecified column widths become zero. Hence, the command «.width» with no arguments resets all column widths to zero and hence causes all column widths to be determined automatically.

The «column» mode is a tabular output format. Other tabular output formats are «box», «markdown», and «table»:

The columnar modes accept some addition options to control formatting. The «—wrap N» option (where N is an integer) causes columns to wrap text that is longer than N characters. Wrapping is disabled if N is zero.

Wrapping happens after exactly N characters, which might be in the middle of a word. To wrap at a word boundary, add the «—wordwrap on» option (or just «-ww» for short):

The «—quote» option causes the results in each column to be quoted like an SQL literal, as in the «quote» mode. See the on-line help for additional options.

The command «.mode box —wrap 60 —quote» is so useful for general-purpose database queries that it is given its own alias. Instead of typing out that whole 27-character command, you can just say «.mode qbox».

Another useful output mode is «insert». In insert mode, the output is formatted to look like SQL INSERT statements. Use insert mode to generate text that can later be used to input data into a different database.

When specifying insert mode, you have to give an extra argument which is the name of the table to be inserted into. For example:

Other output modes include «csv», «json», and «tcl». Try these yourself to see what they do.

6. Querying the database schema

The sqlite3 program provides several convenience commands that are useful for looking at the schema of the database. There is nothing that these commands do that cannot be done by some other means. These commands are provided purely as a shortcut.

For example, to see a list of the tables in the database, you can enter «.tables».

The «.tables» command is similar to setting list mode then executing the following query:

But the «.tables» command does more. It queries the sqlite_schema table for all attached databases, not just the primary database. And it arranges its output into neat columns.

The «.indexes» command works in a similar way to list all of the indexes. If the «.indexes» command is given an argument which is the name of a table, then it shows just indexes on that table.

The «.schema» command shows the complete schema for the database, or for a single table if an optional tablename argument is provided:

The «.schema» command is roughly the same as setting list mode, then entering the following query:

As with «.tables», the «.schema» command shows the schema for all attached databases. If you only want to see the schema for a single database (perhaps «main») then you can add an argument to «.schema» to restrict its output:

The «.schema» command can be augmented with the «—indent» option, in which case it tries to reformat the various CREATE statements of the schema so that they are more easily readable by humans.

The «.databases» command shows a list of all databases open in the current connection. There will always be at least 2. The first one is «main», the original database opened. The second is «temp», the database used for temporary tables. There may be additional databases listed for databases attached using the ATTACH statement. The first output column is the name the database is attached with, and the second result column is the filename of the external file. There may be a third result column which will be either «‘r/o'» or «‘r/w'» depending on whether the database file is read-only or read-write. And there might be a fourth result column showing the result of sqlite3_txn_state() for that database file.

The «.fullschema» dot-command works like the «.schema» command in that it displays the entire database schema. But «.fullschema» also includes dumps of the statistics tables «sqlite_stat1», «sqlite_stat3», and «sqlite_stat4», if they exist. The «.fullschema» command normally provides all of the information needed to exactly recreate a query plan for a specific query. When reporting suspected problems with the SQLite query planner to the SQLite development team, developers are requested to provide the complete «.fullschema» output as part of the trouble report. Note that the sqlite_stat3 and sqlite_stat4 tables contain samples of index entries and so might contain sensitive data, so do not send the «.fullschema» output of a proprietary database over a public channel.

7. Opening Database Files

The «.open» command opens a new database connection, after first closing the previously opened database command. In its simplest form, the «.open» command merely invokes sqlite3_open() on the file named as its argument. Use the name «:memory:» to open a new in-memory database that disappears when the CLI exits or when the «.open» command is run again.

If the —new option is included with «.open», then the database is reset prior to being opened. Any prior data is destroyed. This is a destructive overwrite of prior data and no confirmation is requested, so use this option carefully.

The —readonly option opens the database in read-only mode. Write will be prohibited.

The —deserialize option causes the entire content of the on-disk file to be read into memory and then opened as an in-memory database using the sqlite3_deserialize() interface. This will, of course, require a lot of memory if you have a large database. Also, any changes you make to the database will not be saved back to disk unless you explicitly save them using the «.save» or «.backup» commands.

The —append option causes the SQLite database to be appended to an existing file rather than working as a stand-alone file. See the appendvfs extension for more information.

The —zip option causes the specified input file to be interpreted as a ZIP archive instead of as an SQLite database file.

The —hexdb option causes the database content to be to be read from subsequent lines of input in a hex format, rather than from a separate file on disk. The «dbtotxt» command-line tool can be used to generate the appropriate text for a database. The —hexdb option is intended for use by the SQLite developers for testing purposes. We do not know of any use cases for this option outside of internal SQLite testing and development.

8. Redirecting I/O

8.1. Writing results to a file

By default, sqlite3 sends query results to standard output. You can change this using the «.output» and «.once» commands. Just put the name of an output file as an argument to .output and all subsequent query results will be written to that file. Or use the .once command instead of .output and output will only be redirected for the single next command before reverting to the console. Use .output with no arguments to begin writing to standard output again. For example:

If the first character of the «.output» or «.once» filename is a pipe symbol («|») then the remaining characters are treated as a command and the output is sent to that command. This makes it easy to pipe the results of a query into some other process. For example, the «open -f» command on a Mac opens a text editor to display the content that it reads from standard input. So to see the results of a query in a text editor, one could type:

If the «.output» or «.once» commands have an argument of «-e» then output is collected into a temporary file and the system text editor is invoked on that text file. Thus, the command «.once -e» achieves the same result as «.once ‘|open -f'» but with the benefit of being portable across all systems.

If the «.output» or «.once» commands have a «-x» argument, that causes them to accumulate output as Comma-Separated-Values (CSV) in a temporary file, then invoke the default system utility for viewing CSV files (usually a spreadsheet program) on the result. This is a quick way of sending the result of a query to a spreadsheet for easy viewing:

The «.excel» command is an alias for «.once -x». It does exactly the same thing.

8.2. Reading SQL from a file

In interactive mode, sqlite3 reads input text (either SQL statements or dot-commands) from the keyboard. You can also redirect input from a file when you launch sqlite3, of course, but then you do not have the ability to interact with the program. Sometimes it is useful to run an SQL script contained in a file entering other commands from the command-line. For this, the «.read» dot-command is provided.

The «.read» command takes a single argument which is (usually) the name of a file from which to read input text.

The «.read» command temporarily stops reading from the keyboard and instead takes its input from the file named. Upon reaching the end of the file, input reverts back to the keyboard. The script file may contain dot-commands, just like ordinary interactive input.

If the argument to «.read» begins with the «|» character, then instead of opening the argument as a file, it runs the argument (without the leading «|») as a command, then uses the output of that command as its input. Thus, if you have a script that generates SQL, you can execute that SQL directly using a command similar to the following:

8.3. File I/O Functions

The command-line shell adds two application-defined SQL functions that facilitate reading content from a file into a table column, and writing the content of a column into a file, respectively.

The readfile(X) SQL function reads the entire content of the file named X and returns that content as a BLOB. This can be used to load content into a table. For example:

The writefile(X,Y) SQL function write the blob Y into the file named X and returns the number of bytes written. Use this function to extract the content of a single table column into a file. For example:

Note that the readfile(X) and writefile(X,Y) functions are extension functions and are not built into the core SQLite library. These routines are available as a loadable extension in the ext/misc/fileio.c source file in the SQLite source code repositories.

8.4. The edit() SQL function

The CLI has another built-in SQL function named edit(). Edit() takes one or two arguments. The first argument is a value — often a large multi-line string to be edited. The second argument is the invocation for a text editor. (It may include options to affect the editor’s behavior.) If the second argument is omitted, the VISUAL environment variable is used. The edit() function writes its first argument into a temporary file, invokes the editor on the temporary file, rereads the file back into memory after the editor is done, then returns the edited text.

The edit() function can be used to make changes to large text values. For example:

In this example, the content of the docs.body field for the entry where docs.name is «report-15» will be sent to the editor. After the editor returns, the result will be written back into the docs.body field.

The default operation of edit() is to invoke a text editor. But by using an alternative edit program in the second argument, you can also get it to edit images or other non-text resources. For example, if you want to modify a JPEG image that happens to be stored in a field of a table, you could run:

The edit program can also be used as a viewer, by simply ignoring the return value. For example, to merely look at the image above, you might run:

8.5. Importing files as CSV or other formats

Use the «.import» command to import CSV (comma separated value) or similarly delimited data into an SQLite table. The «.import» command takes two arguments which are the source from which data is to be read and the name of the SQLite table into which the data is to be inserted. The source argument is the name of a file to be read or, if it begins with a «|» character, it specifies a command which will be run to produce the input data.

Note that it may be important to set the «mode» before running the «.import» command. This is prudent to prevent the command-line shell from trying to interpret the input file text as some format other than how the file is structured. If the —csv or —ascii options are used, they control import input delimiters. Otherwise, the delimiters are those in effect for the current output mode.

To import into a table not in the «main» schema, the —schema option may be used to specify that the table is in some other schema. This can be useful for ATTACH’ed databases or to import into a TEMP table.

When .import is run, its treatment of the first input row depends upon whether the target table already exists. If it does not exist, the table is automatically created and the content of the first input row is used to set the name of all the columns in the table. In this case, the table data content is taken from the second and subsequent input rows. If the target table already exists, every row of the input, including the first, is taken to be actual data content. If the input file contains an initial row of column labels, you can make the .import command skip that initial row using the «—skip 1» option.

Here is an example usage, loading a pre-existing temporary table from a CSV file which has column names in its first row:

While reading input data in modes other than ‘ascii’, «.import» interprets input as records composed of fields according to the RFC 4180 specification with this exception: The input record and field separators are as set by the mode or by use of the .separator command. Fields are always subject to quote removal to reverse quoting done per RFC 4180, except in ascii mode.

To import data with arbitrary delimiters and no quoting, first set ascii mode («.mode ascii»), then set the field and record delimiters using the «.separators» command. This will suppress dequoting. Upon «.import», the data will be split into fields and records according to the delimiters so specified.

8.6. Export to CSV

To export an SQLite table (or part of a table) as CSV, simply set the «mode» to «csv» and then run a query to extract the desired rows of the table. The output will formatted as CSV per RFC 4180.

In the example above, the «.headers on» line causes column labels to be printed as the first row of output. This means that the first row of the resulting CSV file will contain column labels. If column labels are not desired, set «.headers off» instead. (The «.headers off» setting is the default and can be omitted if the headers have not been previously turned on.)

The line «.once FILENAME» causes all query output to go into the named file instead of being printed on the console. In the example above, that line causes the CSV content to be written into a file named «C:/work/dataout.csv».

The final line of the example (the «.system c:/work/dataout.csv») has the same effect as double-clicking on the c:/work/dataout.csv file in windows. This will typically bring up a spreadsheet program to display the CSV file.

That command only works as written on Windows. The equivalent line on a Mac would be:

On Linux and other unix systems you will need to enter something like:

8.6.1. Export to Excel

To simplify export to a spreadsheet, the CLI provides the «.excel» command which captures the output of a single query and sends that output to the default spreadsheet program on the host computer. Use it like this:

The command above writes the output of the query as CSV into a temporary file, invokes the default handler for CSV files (usually the preferred spreadsheet program such as Excel or LibreOffice), then deletes the temporary file. This is essentially a short-hand method of doing the sequence of «.csv», «.once», and «.system» commands described above.

The «.excel» command is really an alias for «.once -x». The -x option to .once causes it to writes results as CSV into a temporary file that is named with a «.csv» suffix, then invoke the systems default handler for CSV files.

There is also a «.once -e» command which works similarly, except that it names the temporary file with a «.txt» suffix so that the default text editor for the system will be invoked, instead of the default spreadsheet.

8.6.2. Export to TSV (tab separated values)

Exporting to pure TSV, without any field quoting, can be done by entering «.mode tabs» before running a query. However, the output will not be read correctly in tabs mode by the «.import» command if it contains doublequote characters. To get TSV quoted per RFC 4180 so that it can be input in tabs mode with «.import», first enter «.mode csv», then enter ‘.separator «\t»‘ before running a query.

9. Accessing ZIP Archives As Database Files

In addition to reading and writing SQLite database files, the sqlite3 program will also read and write ZIP archives. Simply specify a ZIP archive filename in place of an SQLite database filename on the initial command line, or in the «.open» command, and sqlite3 will automatically detect that the file is a ZIP archive instead of an SQLite database and will open it as such. This works regardless of file suffix. So you can open JAR, DOCX, and ODP files and any other file format that is really a ZIP archive and SQLite will read it for you.

A ZIP archive appears to be a database containing a single table with the following schema:

So, for example, if you wanted to see the compression efficiency (expressed as the size of the compressed content relative to the original uncompressed file size) for all files in the ZIP archive, sorted from most compressed to least compressed, you could run a query like this:

Or using file I/O functions, you can extract elements of the ZIP archive:

9.1. How ZIP archive access is implemented

The command-line shell uses the Zipfile virtual table to access ZIP archives. You can see this by running the «.schema» command when a ZIP archive is open:

When opening a file, if the command-line client discovers that the file is ZIP archive instead of an SQLite database, it actually opens an in-memory database and then in that in-memory database it creates an instance of the Zipfile virtual table that is attached to the ZIP archive.

The special processing for opening ZIP archives is a trick of the command-line shell, not the core SQLite library. So if you want to open a ZIP archive as a database in your application, you will need to activate the Zipfile virtual table module then run an appropriate CREATE VIRTUAL TABLE statement.

10. Converting An Entire Database To A Text File

Use the «.dump» command to convert the entire contents of a database into a single UTF-8 text file. This file can be converted back into a database by piping it back into sqlite3.

A good way to make an archival copy of a database is this:

This generates a file named ex1.dump.gz that contains everything you need to reconstruct the database at a later time, or on another machine. To reconstruct the database, just type:

The text format is pure SQL so you can also use the .dump command to export an SQLite database into other popular SQL database engines. Like this:

11. Recover Data From a Corrupted Database

Like the «.dump» command, «.recover» attempts to convert the entire contents of a database file to text. The difference is that instead of reading data using the normal SQL database interface, «.recover» attempts to reassemble the database based on data extracted directly from as many database pages as possible. If the database is corrupt, «.recover» is usually able to recover data from all uncorrupted parts of the database, whereas «.dump» stops when the first sign of corruption is encountered.

If the «.recover» command recovers one or more rows that it cannot attribute to any database table, the output script creates a «lost_and_found» table to store the orphaned rows. The schema of the lost_and_found table is as follows:

The «lost_and_found» table contains one row for each orphaned row recovered from the database. Additionally, there is one row for each recovered index entry that cannot be attributed to any SQL index. This is because, in an SQLite database, the same format is used to store SQL index entries and WITHOUT ROWID table entries.

If the recovered database schema already contains a table named «lost_and_found», the «.recover» command uses the name «lost_and_found0». If the name «lost_and_found0» is also already taken, «lost_and_found1», and so on. The default name «lost_and_found» may be overridden by invoking «.recover» with the —lost-and-found switch. For example, to have the output script call the table «orphaned_rows»:

12. Loading Extensions

You can add new custom application-defined SQL functions, collating sequences, virtual tables, and VFSes to the command-line shell at run-time using the «.load» command. First, build the extension as a DLL or shared library (as described in the Run-Time Loadable Extensions document) then type:

Note that SQLite automatically adds the appropriate extension suffix («.dll» on windows, «.dylib» on Mac, «.so» on most other unixes) to the extension filename. It is generally a good idea to specify the full pathname of the extension.

SQLite computes the entry point for the extension based on the extension filename. To override this choice, simply add the name of the extension as a second argument to the «.load» command.

Source code for several useful extensions can be found in the ext/misc subdirectory of the SQLite source tree. You can use these extensions as-is, or as a basis for creating your own custom extensions to address your own particular needs.

13. Cryptographic Hashes Of Database Content

The «.sha3sum» dot-command computes a SHA3 hash of the content of the database. To be clear, the hash is computed over the database content, not its representation on disk. This means, for example, that a VACUUM or similar data-preserving transformation does not change the hash.

The «.sha3sum» command supports options «—sha3-224», «—sha3-256», «—sha3-384», and «—sha3-512» to define which variety of SHA3 to use for the hash. The default is SHA3-256.

The database schema (in the sqlite_schema table) is not normally included in the hash, but can be added by the «—schema» option.

The «.sha3sum» command takes a single optional argument which is a LIKE pattern. If this option is present, only tables whose names match the LIKE pattern will be hashed.

The «.sha3sum» command is implemented with the help of the extension function «sha3_query()» that is included with the command-line shell.

14. Database Content Self-Tests

The «.selftest» command attempts to verify that a database is intact and is not corrupt. The .selftest command looks for a table in schema named «selftest» and defined as follows:

The .selftest command reads the rows of the selftest table in selftest.tno order. For each ‘memo’ row, it writes the text in ‘cmd’ to the output. For each ‘run’ row, it runs the ‘cmd’ text as SQL and compares the result to the value in ‘ans’, and shows an error message if the results differ.

If there is no selftest table, the «.selftest» command runs PRAGMA integrity_check.

The «.selftest —init» command creates the selftest table if it does not already exists, then appends entries that check the SHA3 hash of the content of all tables. Subsequent runs of «.selftest» will verify that the database has not been changed in any way. To generate tests to verify that a subset of the tables is unchanged, simply run «.selftest —init» then DELETE the selftest rows that refer to tables that are not constant.

15. SQLite Archive Support

The «.archive» dot-command and the «-A» command-line option provide built-in support for the SQLite Archive format. The interface is similar to that of the «tar» command on unix systems. Each invocation of the «.ar» command must specify a single command option. The following commands are available for «.archive»:

As well as the command option, each invocation of «.ar» may specify one or more modifier options. Some modifier options require an argument, some do not. The following modifier options are available:

For command-line usage, add the short style command-line options immediately following the «-A», without an intervening space. All subsequent arguments are considered to be part of the .archive command. For example, the following commands are equivalent:

Long and short style options may be mixed. For example, the following are equivalent:

Alternatively, the first argument following to «.ar» may be the concatenation of the short form of all required options (without the «-» characters). In this case arguments for options requiring them are read from the command line next, and any remaining words are considered command arguments. For example:

15.1. SQLite Archive Create Command

Create a new archive, overwriting any existing archive (either in the current «main» db or in the file specified by a —file option). Each argument following the options is a file to add to the archive. Directories are imported recursively. See above for examples.

15.2. SQLite Archive Extract Command

Extract files from the archive (either to the current working directory or to the directory specified by a —directory option). Files or directories whose names match the arguments, as affected by the —glob option, are extracted. Or, if no arguments follow the options, all files and directories are extracted. Any specified directories are extracted recursively. It is an error if any specified names or match patterns cannot be found in the archive.

15.3. SQLite Archive List Command

List the contents of the archive. If no arguments are specified, then all files are listed. Otherwise, only those which match the arguments, as affected by the —glob option, are listed. Currently, the —verbose option does not change the behaviour of this command. That may change in the future.

15.4. SQLite Archive Insert And Update Commands

The —update and —insert commands work like —create command, except that they do not delete the current archive before commencing. New versions of files silently replace existing files with the same names, but otherwise the initial contents of the archive (if any) remain intact.

For the —insert command, all files listed are inserted into the archive. For the —update command, files are only inserted if they do not previously exist in the archive, or if their «mtime» or «mode» is different from what is currently in the archive.

Compatibility node: Prior to SQLite version 3.28.0 (2019-04-16) only the —update option was supported but that option worked like —insert in that it always reinserted every file regardless of whether or not it had changed.

15.5. SQLite Archive Remove Command

The —remove command deletes files and directories which match the provided arguments (if any) as affected by the —glob option. It is an error to provide arguments which match nothing in the archive.

15.6. Operations On ZIP Archives

If FILE is a ZIP archive rather than an SQLite Archive, the «.archive» command and the «-A» command-line option still work. This is accomplished using of the zipfile extension. Hence, the following commands are roughly equivalent, differing only in output formatting:

15.7. SQL Used To Implement SQLite Archive Operations

The various SQLite Archive Archive commands are implemented using SQL statements. Application developers can easily add SQLite Archive Archive reading and writing support to their own projects by running the appropriate SQL.

To see what SQL statements are used to implement an SQLite Archive operation, add the —dryrun or -n option. This causes the SQL to be displayed but inhibits the execution of the SQL.

The SQL statements used to implement SQLite Archive operations make use of various loadable extensions. These extensions are all available in the SQLite source tree in the ext/misc/ subfolder. The extensions needed for full SQLite Archive support include:

fileio.c — This extension adds SQL functions readfile() and writefile() for reading and writing content from files on disk. The fileio.c extension also includes fsdir() table-valued function for listing the contents of a directory and the lsmode() function for converting numeric st_mode integers from the stat() system call into human-readable strings after the fashion of the «ls -l» command.

sqlar.c — This extension adds the sqlar_compress() and sqlar_uncompress() functions that are needed to compress and uncompress file content as it is inserted and extracted from an SQLite Archive.

zipfile.c — This extension implements the «zipfile(FILE)» table-valued function which is used to read ZIP archives. This extension is only needed when reading ZIP archives instead of SQLite archives.

appendvfs.c — This extension implements a new VFS that allows an SQLite database to be appended to some other file, such as an executable. This extension is only needed if the —append option to the .archive command is used.

16. SQL Parameters

SQLite allows bound parameters to appear in an SQL statement anywhere that a literal value is allowed. The values for these parameters are set using the sqlite3_bind_. () family of APIs.

Parameters can be either named or unnamed. An unnamed parameter is a single question mark («?»). Named parameters are a «?» followed immediately by a number (ex: «?15» or «?123») or one of the characters «$», «:», or «@» followed by an alphanumeric name (ex: «$var1», «:xyz», «@bingo»).

This command-line shell leaves unnamed parameters unbound, meaning that they will have a value of an SQL NULL, but named parameters might be assigned values. If there exists a TEMP table named «sqlite_parameters» with a schema like this:

And if there is an entry in that table where the key column exactly matches the name of parameter (including the initial «?», «$», «:», or «@» character) then the parameter is assigned the value of the value column. If no entry exists, the parameter defaults to NULL.

The «.parameter» command exists to simplify managing this table. The «.parameter init» command (often abbreviated as just «.param init») creates the temp.sqlite_parameters table if it does not already exist. The «.param list» command shows all entries in the temp.sqlite_parameters table. The «.param clear» command drops the temp.sqlite_parameters table. The «.param set KEY VALUE» and «.param unset KEY» commands create or delete entries from the temp.sqlite_parameters table.

The VALUE passed to «.param set KEY VALUE» can be either a SQL literal or any other SQL expression or query which can be evaluated to yield a value. This allows values of differing types to be set. If such evaluation fails, the provided VALUE is instead quoted and inserted as text. Because such initial evaluation may or may not fail depending upon the VALUE content, the reliable way to get a text value is to enclose it with single-quotes protected from the above-described command-tail parsing. For example, (unless one intends a value of -1365):

Note that the double-quotes serve to protect the single-quotes and ensure that the quoted text is parsed as one argument.

The temp.sqlite_parameters table only provides values for parameters in the command-line shell. The temp.sqlite_parameter table has no effect on queries that are run directly using the SQLite C-language API. Individual applications are expected to implement their own parameter binding. You can search for «sqlite_parameters» in the command-line shell source code to see how the command-line shell does parameter binding, and use that as a hint for how to implement it yourself.

17. Index Recommendations (SQLite Expert)

Note: This command is experimental. It may be removed or the interface modified in incompatible ways at some point in the future.

For most non-trivial SQL databases, the key to performance is creating the right SQL indexes. In this context «the right SQL indexes» means those that cause the queries that an application needs to optimize run fast. The «.expert» command can assist with this by proposing indexes that might assist with specific queries, were they present in the database.

The «.expert» command is issued first, followed by the SQL query on a separate line. For example, consider the following session:

In the above, the user creates the database schema (a single table — «x1»), and then uses the «.expert» command to analyze a query, in this case «SELECT * FROM x1 WHERE a=? AND b>?». The shell tool recommends that the user create a new index (index «x1_idx_000123a7») and outputs the plan that the query would use in EXPLAIN QUERY PLAN format. The user then creates an index with an equivalent schema and runs the analysis on the same query again. This time the shell tool does not recommend any new indexes, and outputs the plan that SQLite will use for the query given the existing indexes.

The «.expert» command accepts the following options:

The functionality described in this section may be integrated into other applications or tools using the SQLite expert extension code.

A database schema which incorporate SQL custom functions made available via the extension load mechanism may need special provision to work with the .expert feature. Because the feature uses additional connections to implement its functionality, those custom functions must be made available to those additional connections. This can be done by means of the extension load/usage options described at Automatically Load Statically Linked Extensions and Persistent Loadable Extensions.

18. Working With Multiple Database Connections

Beginning with version 3.37.0 (2021-11-27), the CLI has the ability to hold multiple database connections open at once. Only one database connection is active at a time. The inactive connections are still open but are idle.

Use the «.connection» dot-command (often abbreviated as just «.conn») to see a list of database connections and an indication of which one is currently active. Each database connection is identified by an integer between 0 and 9. (There can be at most 10 simultaneously open connections.) Change to another database connection, creating it if it does not already exist, by typing the «.conn» command followed by its number. Close a database connection by typing «.conn close N» where N is the connection number.

Though the underlying SQLite database connections are completely independent of one another, many of the CLI settings, such as the output format, are shared across all database connections. Thus, changing the output mode in one connection will change it in them all. On the other hand, some dot-commands such as .open only affect the current connection.

19. Miscellaneous Extension Features

The CLI is built with several SQLite extensions that are not included with the SQLite library. A few add features not described in the preceding sections, namely:

• the UINT collating sequence which treats unsigned integers embedded in text according to their value, along with other text, for ordering;
• decimal arithmetic as provided by the decimal extension;
• the generate_series() table-valued function;
• the base64() and base85() functions which encode a blob to base64 or base85 text or decode the same to a blob; and
• support for POSIX extended regular expressions bound to the REGEXP operator.

20. Other Dot Commands

There are many other dot-commands available in the command-line shell. See the «.help» command for a complete list for any particular version and build of SQLite.

21. Using sqlite3 in a shell script

One way to use sqlite3 in a shell script is to use «echo» or «cat» to generate a sequence of commands in a file, then invoke sqlite3 while redirecting input from the generated command file. This works fine and is appropriate in many circumstances. But as an added convenience, sqlite3 allows a single SQL command to be entered on the command line as a second argument after the database name. When the sqlite3 program is launched with two arguments, the second argument is passed to the SQLite library for processing, the query results are printed on standard output in list mode, and the program exits. This mechanism is designed to make sqlite3 easy to use in conjunction with programs like «awk». For example:

22. Marking The End Of An SQL Statement

SQLite commands are normally terminated by a semicolon. In the CLI you can also use the word «GO» (case-insensitive) or a slash character «/» on a line by itself to end a command. These are used by SQL Server and Oracle, respectively, and are supported by the SQLite CLI for compatibility. These won’t work in sqlite3_exec(), because the CLI translates these inputs into a semicolon before passing them down into the SQLite core.

23. Command-line Options

There are many command-line options available to the CLI. Use the —help command-line option to see a list:

The CLI is flexible regarding command-line option formatting. Either one or two leading «-» characters are permitted. Thus «-box» and «—box» mean the same thing. Command-line options are processed from left to right. Hence a «—box» option will override a prior «—quote» option.

Most of the command-line options are self-explanatory, but a few merit additional discussion below.

23.1. The —safe command-line option

The —safe command-line option attempts to disable all features of the CLI that might cause any changes to the host computer other than changes to the specific database file named on the command-line. The idea is that if you receive a large SQL script from an unknown or untrusted source, you can run that script to see what it does without risking an exploit by using the —safe option. The —safe option disables (among other things):

• The .open command, unless the —hexdb option is used or the filename is «:memory:». This prevents the script from reading or writing any database files not named on the original command-line.
• The ATTACH SQL command.
• SQL functions that have potentially harmful side-effects, such as edit(), fts3_tokenizer(), load_extension(), readfile() and writefile().
• The .archive command.
• The .backup and .save commands.
• The .import command.
• The .load command.
• The .log command.
• The .shell and .system commands.
• The .excel, .once and .output commands.
• Other commands that can have deleterious side effects.

Basically, any feature of the CLI that reads or writes from a file on disk other than the main database file is disabled.

23.1.1. Bypassing —safe restrictions for specific commands

If the «—nonce NONCE» option is also included on the command-line, for some large and arbitrary NONCE string, then the «.nonce NONCE» command (with the same large nonce string) will permit the next SQL statement or dot-command to bypass the —safe restrictions.

Suppose you want to run a suspicious script and the script requires one or two of the features that —safe normally disables. For example, suppose it needs to ATTACH one additional database. Or suppose the script needs to load a specific extension. This can be accomplished by preceding the (carefully audited) ATTACH statement or the «.load» command with an appropriate «.nonce» command and supplying the same nonce value using the «—nonce» command-line option. Those specific commands will then be allowed to execute normally, but all other unsafe commands will still be restricted.

The use of «.nonce» is dangerous in the sense that a mistake can allow a hostile script to damage your system. Therefore, use «.nonce» carefully, sparingly, and as a last resort when there are no other ways to get a script to run under —safe mode.

24. Compiling the sqlite3 program from sources

To compile the command-line shell on unix systems and on Windows with MinGW, the usual configure-make command works:

The configure-make works whether you are building from the canonical sources from the source tree, or from an amalgamated bundle. There are few dependencies. When building from canonical sources, a working tclsh is required. If using an amalgamation bundle, all the preprocessing work normally done by tclsh will have already been carried out and only normal build tools are required.

A working zlib compression library is needed in order for the .archive command to operate.

On Windows with MSVC, use nmake with the Makefile.msc:

For correct operation of the .archive command, make a copy of the zlib source code into the compat/zlib subdirectory of the source tree and compile this way:

24.1. Do-It-Yourself Builds

The source code to the sqlite3 command line interface is in a single file named «shell.c». The shell.c source file is generated from other sources, but most of the code for shell.c can be found in src/shell.c.in. (Regenerate shell.c by typing «make shell.c» from the canonical source tree.) Compile the shell.c file (together with the sqlite3 library source code) to generate the executable. For example:

The following additional compile-time options are recommended in order to provide a full-featured command-line shell:

• -DSQLITE_THREADSAFE=0
• -DSQLITE_ENABLE_EXPLAIN_COMMENTS
• -DSQLITE_HAVE_ZLIB
• -DSQLITE_INTROSPECTION_PRAGMAS
• -DSQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
• -DSQLITE_ENABLE_STMTVTAB
• -DSQLITE_ENABLE_DBPAGE_VTAB
• -DSQLITE_ENABLE_DBSTAT_VTAB
• -DSQLITE_ENABLE_OFFSET_SQL_FUNC
• -DSQLITE_ENABLE_JSON1
• -DSQLITE_ENABLE_RTREE
• -DSQLITE_ENABLE_FTS4
• -DSQLITE_ENABLE_FTS5

This page last modified on 2023-02-17 15:36:25 UTC