In PostgreSQL, selecting a database is an essential step before executing queries. The `\c` command in psql is used to connect to a specific database.

Connecting to a Database:

Use the `\c database_name` command to switch to another database. This command establishes a connection to the specified database.


-- Connect to a database named 'my_database'
\c my_database

Listing Available Databases:

To view all available databases, use the `\l` command in the psql terminal. This lists all databases present in the PostgreSQL server.


-- List all databases
\l

Checking Current Database:

You can check which database you are currently connected to by using the `SELECT current_database();` query.


-- Check current database
SELECT current_database();

Switching Databases Within a Session:

Switching databases within a session is possible using the `\c` command without needing to restart the session.


-- Switch to another database
\c another_database

Using SQL Shell (psql):

The SQL Shell (psql) is a powerful tool to manage PostgreSQL databases. It allows executing SQL queries and database management commands.


-- Start psql shell
psql -U username -d database_name

Environment Configuration:

Ensure that your PostgreSQL environment is correctly set up with necessary permissions to access and switch databases.


-- Check environment settings
SHOW ALL;

Database Connection Strings:

Connection strings can be used in applications to connect to PostgreSQL databases. They include the database name, user, password, and host information.


-- Example connection string
postgresql://username:password@localhost:5432/my_database

Using GUI Tools:

Graphical tools like pgAdmin can also be used to select and manage databases visually, providing a user-friendly interface.


-- Open pgAdmin and navigate to the database section

Database Roles and Permissions:

Ensure that the user role has the necessary permissions to connect to and manage the selected database.


-- Grant permissions to a user
GRANT CONNECT ON DATABASE my_database TO my_user;

Console Output Example:

You are now connected to database "my_database" as user "username".