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17 Practical psql Commands You Don’t Want to Miss

Summary: In this tutorial, you will learn how to use practical psql commands to interact with the PostgreSQL database server effectively.

1) Connect to PostgreSQL database​

The following command connects to a database under a specific user. After pressing Enter PostgreSQL will ask for the password of the user.

psql -d database -U  user -W

For example, to connect to dvdrental database under postgres user, you use the following command:

psql -d dvdrental -U postgres -W
Password for user postgres:
dvdrental=#

If you want to connect to a database that resides on another host, you add the -h option as follows:

psql -h host -d database -U user -W

In case you want to use SSL mode for the connection, just specify it as shown in the following command:

psql -U user -h host "dbname=db sslmode=require"

2) Switch connection to a new database​

Once you are connected to a database, you can switch the connection to a new database under a user-specified by user. The previous connection will be closed. If you omit the user parameter, the current user is assumed.

\c dbname username

The following command connects to dvdrental database under postgres user:

postgres=# \c dvdrental
You are now connected to database "dvdrental" as user "postgres".
dvdrental=#

3) List available databases​

To list all databases in the current PostgreSQL database server, you use \l command:

\l

4) List available tables​

To list all tables in the current database, you use the \dt command:

\dt

Note that this command shows the only table in the currently connected database.

5) Describe a table​

To describe a table such as a column, type, or modifiers of columns, you use the following command:

\d table_name

6) List available schema​

To list all schemas of the currently connected database, you use the \dn command.

\dn

7) List available functions​

To list available functions in the current database, you use the \df command.

\df

8) List available views​

To list available views in the current database, you use the \dv command.

\dv

9) List users and their roles​

To list all users and their assigned roles, you use \du command:

\du

10) Execute the previous command​

To retrieve the current version of PostgreSQL server, you use the version() function as follows:

SELECT version();

Now, if you want to save time typing the previous command again, you can use \g command to execute the previous command:

\g

psql executes the previous command again, which is the SELECT statement,.

11) Command history​

To display command history, you use the \s command.

\s

If you want to save the command history to a file, you need to specify the file name followed the \s command as follows:

\s filename

12) Execute psql commands from a file​

In case you want to execute psql commands from a file, you use \i command as follows:

\i filename

13) Get help on psql commands​

To know all available psql commands, you use the \? command.

\?

To get help on specific PostgreSQL statement, you use the \h command.

For example, if you want to know detailed information on the ALTER TABLE statement, you use the following command:

\h ALTER TABLE

14) Turn on query execution time​

To turn on query execution time, you use the \timing command.

dvdrental=# \timing
Timing is on.
dvdrental=# select count(*) from film;
 count
-------
  1000
(1 row)

Time: 1.495 ms
dvdrental=#

You use the same command \timing to turn it off.

dvdrental=# \timing
Timing is off.
dvdrental=#

15) Edit command in your editor​

It is very handy if you can type the command in your favorite editor. To do this in psql, you \e command. After issuing the command, psql will open the text editor defined by your EDITOR environment variable and place the most recent command that you entered in psql into the editor.

psql commandsAfter you type the command in the editor, save it, and close the editor, psql will execute the command and return the result.

psql command example It is more useful when you edit a function in the editor.

\ef [function name]

psql commadn ef edit function

16) Switch output options​

psql supports some types of output format and allows you to customize how the output is formatted on the fly.

  • \a command switches from aligned to non-aligned column output.
  • \H command formats the output to HTML format.

17) Quit psql​

To quit psql, you use \q command and press Enter to exit psql.

\q

In this tutorial, you have learned how to use psql commands to perform various commonly used tasks in PostgreSQL.