How to USE in PostgreSQL

Why doesn’t USE work in PostgreSQL?

PostgreSQL treats databases as separate server-level objects; standard SQL has no USE command. Instead, psql offers the meta-command \c (or \connect) to switch databases within the same server connection.

How do I switch databases in psql?

Run \c target_db (or \c target_db username if you need a different role). The prompt changes to confirm the new database.

Can I switch databases inside a SQL script?

Add \c target_db on its own line. Because \c is a psql directive, the file must be executed with psql, not via a client library that only interprets SQL.

How do I reconnect with a URL?

If you are outside psql, reconnect using your driver’s connection string: postgresql://user:pass@host:5432/target_db. Switching requires a new connection.

What are common use cases?

1. Jumping between ecommerce_dev and ecommerce_prod during debugging.
2. Running maintenance tasks on a staging database without opening a new terminal.
3. Loading data into throw-away scratch databases for ad-hoc analysis.

Best practices for switching databases

• Use dedicated roles per environment (app_dev, app_prod) and pass the role to \c.
• Keep automated scripts environment-specific; avoid mid-script switches to reduce risk.
• In CI pipelines, open a fresh connection rather than \c to make logs clearer.

How do I verify the current database?

Run SELECT current_database(); or check the psql prompt, which shows dbname=>.