psql command-line tool basics in PostgreSQL - Cheat Sheet & Quick Revision

Recall & Review

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What is psql in PostgreSQL?

psql is a command-line tool that lets you interact with a PostgreSQL database by typing commands and queries directly.

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How do you connect to a PostgreSQL database using psql?

Use the command psql -d database_name -U username. This opens a session connected to the specified database as the given user.

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What does the command \q do in psql?

\q quits the psql tool and ends your session.

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How can you list all tables in the current database using psql?

Type \dt to see a list of all tables in the connected database.

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What is the purpose of the command \? in psql?

\? shows help information listing all available psql commands and their descriptions.

Which command exits the psql tool?

A exit()

B \exit

C \q

D quit

The command \q is the correct way to quit psql. Other options are not valid commands in psql.

How do you list all tables in the current database in psql?

A \dt

B \list

C \tables

D \show tables

\dt lists all tables. \list shows databases, and the others are not valid psql commands.

What does the command psql -d mydb -U user1 do?

A Connects to the database mydb as user1

B Creates a new database named mydb

C Deletes the database mydb

D Lists all users in the database

This command connects you to the database mydb as the user user1.

Which command shows help information about psql commands?

A \help

B help()

C man psql

D \?

\? displays help for psql commands. man psql shows the manual but outside psql.

If you want to run a SQL query in psql, what must you end the query with?

A A period (.)

B A semicolon (;)

C A comma (,)

D No special character needed

SQL queries in psql must end with a semicolon ; to execute.

Explain how to start a psql session to connect to a PostgreSQL database.

Think about the command format to open <code>psql</code> with database and user.

List three useful psql meta-commands and what they do.

Meta-commands start with a backslash \.