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The sqlite3 command line tool

In this part of the SQLite tutorial, we will cover the sqlite3 command line tool.

The SQLite manual describes sqlite3 as as a terminal-based front-end to the SQLite library that can evaluate queries interactively and display the results in multiple formats. The sqlite3 can also be used within shell scripts and other applications to provide batch processing features.

sqlite3 tool

sqlite3 is a terminal based frontend to the SQLite library that can evaluate queries interactively and display the results in multiple formats. It can also be used within scripts.

On the terminal screen, we see the following prompt of the sqlite3 tool.

$ sqlite3 test.db 
SQLite version 3.7.7 2011-06-23 19:49:22
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite>

The .help command is one of the metacommnads of the sqlite3 tool. It lists all metacommands. The .exit and the .quit commands exit the sqlite3 session. We can also use the Ctrl+Q key combination to quit sqlite3. The .databases command shows the attached databases. The .tables command lists the available tables.

Creating a database

The complete SQLite database is stored in a single cross-platform disk file. We use the sqlite3 command line tool to create a new database file.

$ sqlite3 movies.db

Here we create a new movies.db database. If the exists, it is opened.

Basic sqlite3 metacommnads

Next we describe some of the metacommands of the sqlite3 tool.

sqlite> .tables
Books         Customers     Log           Orders        Testing     
Cars          Friends       Names         Reservations

The .tables commnad shows the available tables.

sqlite> SELECT * FROM Friends;
1|Jane|F
2|Thomas|M
3|Frank|M
4|Elisabeth|F
5|Mary|F
6|Lucy|F
7|Jack|M

Here we get the output of a simple SELECT statement. By default, the output mode is line and the separator is |.

sqlite> .separator :
sqlite> SELECT * FROM Friends;
1:Jane:F
2:Thomas:M
3:Frank:M
4:Elisabeth:F
5:Mary:F
6:Lucy:F
7:Jack:M

Here we have used a new colon separator.

There are several other output modes available. The following example shows the column output mode.

sqlite> .mode column
sqlite> .headers on
sqlite> SELECT * FROM Friends;
Id          Name        Sex       
----------  ----------  ----------
1           Jane        F         
2           Thomas      M         
3           Frank       M         
4           Elisabeth   F         
5           Mary        F         
6           Lucy        F         
7           Jack        M  

This example shows how data is formatted in sqlite's column mode. The .headers command has also been used to show column headers. By default, the headers are hidden.

The .width command adjusts the size of the columns.

sqlite> SELECT Title, Author FROM Books;
Title          Author     
-------------  -----------
War and Peace  Leo Tolstoy
The Brothers   Fyodor Dost
Crime and Pun  Fyodor Dost

Here, the column widths are not wide enough to display all data correctly.

sqlite> .width 22, 18
sqlite> SELECT Title, Author FROM Books;
Title                   Author            
----------------------  ------------------
War and Peace           Leo Tolstoy       
The Brothers Karamazov  Fyodor Dostoyevsky
Crime and Punishment    Fyodor Dostoyevsky

Here we change the column widths. The first column will be 22 characters wide, the second 18.

sqlite> .show
     echo: off
  explain: off
  headers: on
     mode: column
nullvalue: ""
   output: stdout
separator: "|"
    stats: off
    width: 22 18 

The .show command lists various settings. These include the output mode, the separator used in the list mode, and whether the headers are on.

sqlite> .schema Cars
CREATE TABLE Cars(Id integer primary key, Name text, Cost integer);

The .schema command shows the structure of the table. It gives the DDL SQL to create the table.

Executing SQL from the shell

We can execute SQL commands from the shell.

$ sqlite3 test.db "SELECT * FROM Cars;"
1|Audi|52642
2|Mercedes|57127
3|Skoda|9000
4|Volvo|29000
5|Bentley|350000
6|Citroen|21000
7|Hummer|41400
8|Volkswagen|21600  

Here we have non-interactively executed a SELECT SQL command. We selected all cars from the Cars table.

Dumping tables

It is possible to dump tables in SQL format to the disk. This way we can easily save the structure and the data of a database table.

We have the Cars table.

sqlite> SELECT * FROM Cars;
Id          Name        Cost      
----------  ----------  ----------
1           Audi        52642     
2           Mercedes    57127     
3           Skoda       9000      
4           Volvo       29000     
5           Bentley     350000    
6           Citroen     21000     
7           Hummer      41400     
8           Volkswagen  21600   

Now, we are going to use the .dump command to dump the table.

sqlite> .dump Cars
PRAGMA foreign_keys=OFF;
BEGIN TRANSACTION;
CREATE TABLE Cars(Id integer primary key, Name text, Cost integer);
INSERT INTO "Cars" VALUES(1,'Audi',52642);
INSERT INTO "Cars" VALUES(2,'Mercedes',57127);
INSERT INTO "Cars" VALUES(3,'Skoda',9000);
INSERT INTO "Cars" VALUES(4,'Volvo',29000);
INSERT INTO "Cars" VALUES(5,'Bentley',350000);
INSERT INTO "Cars" VALUES(6,'Citroen',21000);
INSERT INTO "Cars" VALUES(7,'Hummer',41400);
INSERT INTO "Cars" VALUES(8,'Volkswagen',21600);
COMMIT;

The .dump command shows us the SQL necessary to recreate the table.

sqlite> .output cars2.sql
sqlite> .dump Cars

We can also redirect the output to a file. The .output command will redirect the output to the cars2.sql file.

$ cat cars2.sql 
PRAGMA foreign_keys=OFF;
BEGIN TRANSACTION;
CREATE TABLE Cars(Id integer primary key, Name text, Cost integer);
INSERT INTO "Cars" VALUES(1,'Audi',52642);
...

We verify it.

Reading SQL

We can read SQL from a file name with the .read commnad.

sqlite> .tables Cars
Cars
sqlite> DROP TABLE CARS;
sqlite> .tables Cars
sqlite> .read cars.sql 
sqlite> .tables Cars
Cars
sqlite> SELECT * FROM Cars WHERE id=1;
Id          Name        Cost      
----------  ----------  ----------
1           Audi        52642     

Here we have executed a series of commands. We drop the table and read it from the cars.sql.

$ tail -5 ~/.sqlite_history 
SELECT * FROM Cars LIMIT 2;
.help
.tables
.echo ON
SELECT * FROM Cars;

The commands and statements are archived in the .sqlite_history file, located in the home directory. Using the tail command, we show the last five entries.

Resource file

The sqlite3 tool has a resource file called .sqliterc. It is located in the home directory. If there is no such file, we can simply create it. We can place the meta commnads there or the regular SQL statements. However, we should avoid using SQL in the resource file.

$ cat .sqliterc 
.mode column
.header on
.nullvalue NULL  

Here is a simple example of a resource file. It has three meta commands. With resource file, we don't have to execute meta commnads all over again, when we start the sqlite3 tool. They will be executed automatically at the start of the tool.

$ sqlite3 test.db 
-- Loading resources from /home/janbodnar/.sqliterc
SQLite version 3.7.7 2011-06-23 19:49:22
Enter ".help" for instructions
Enter SQL statements terminated with a ";"

We have a message saying that the tool loaded resources upon the beginning.

Command line options

The tool has several command line options. They mostly duplicate the meta commands. Note that commnad line options overwrite the resource file metacommands.

$ sqlite3 -help
Usage: sqlite3 [OPTIONS] FILENAME [SQL]
FILENAME is the name of an SQLite database. A new database is created
if the file does not previously exist.
OPTIONS include:
   -help                show this message
   -init filename       read/process named file
   -echo                print commands before execution
   -[no]header          turn headers on or off
   -bail                stop after hitting an error
   -interactive         force interactive I/O
   -batch               force batch I/O
   -column              set output mode to 'column'
   -csv                 set output mode to 'csv'
   -html                set output mode to HTML
   -line                set output mode to 'line'
   -list                set output mode to 'list'
   -separator 'x'       set output field separator (|)
   -stats               print memory stats before each finalize
   -nullvalue 'text'    set text string for NULL values
   -version             show SQLite version
   -vfs NAME            use NAME as the default VFS

The -help options gives us the list of all available options with a brief description.

$ sqlite3 -echo -line -noheader test.db 
SQLite version 3.7.7 2011-06-23 19:49:22
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> SELECT * FROM Cars LIMIT 2;
SELECT * FROM Cars LIMIT 2;
   Id = 1
 Name = Audi
 Cost = 52642

   Id = 2
 Name = Mercedes
 Cost = 57127

We start the sqlite3 tool with -echo, -line and -noheader options. The SELECT command is repeated/echoed after being launched. The ouput is in the line mode and we have no headers.

$ sqlite3 -version
-- Loading resources from /home/janbodnar/.sqliterc
3.7.7 2011-06-23 19:49:22 4374b7e83ea0a3fbc3691f9c0c936272862f32f

We get the sqlite3 version.

$ sqlite3 -html test.db
-- Loading resources from /home/janbodnar/.sqliterc
SQLite version 3.7.7 2011-06-23 19:49:22
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> SELECT * FROM Cars LIMIT 2;
<TR><TH>Id</TH><TH>Name</TH><TH>Cost</TH></TR>
<TR><TD>1</TD>
<TD>Audi</TD>
<TD>52642</TD>
</TR>
<TR><TD>2</TD>
<TD>Mercedes</TD>
<TD>57127</TD>
</TR>

The -html option causes the results to be output as simple HTML tables.

In this part of the SQLite tutorial, we worked with the sqlite3 command line tool. We have described various metacommnads. We have shown how to dump tables and read SQL from files. We described the sqlite's resource file.