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PostgreSQL DROP TABLE

The DROP TABLE statement removes an entire table and all its data from the database. This is a permanent action and cannot be easily reversed.

Key Topics

1. DROP TABLE Syntax

DROP TABLE table_name;

This removes the specified table and all associated data. Once dropped, the data cannot be recovered unless you have a backup.

2. IF EXISTS Clause

Use IF EXISTS to avoid an error if the table does not exist:

DROP TABLE IF EXISTS old_table;

This prevents the command from failing and displays a warning instead of an error if old_table isn’t present.

3. CASCADE vs. RESTRICT

The CASCADE option removes dependent objects (e.g., views or foreign key constraints) automatically, while RESTRICT prevents dropping if dependencies exist.

DROP TABLE table_name CASCADE;

Use CASCADE carefully as it can remove multiple objects. RESTRICT is the default behavior.

Best Practices

  • Always back up critical data before dropping tables in production.
  • Check for dependencies, such as foreign keys and views, before dropping.
  • Use IF EXISTS to avoid errors in scripts where the table may not exist.

Key Takeaways

  • DROP TABLE is irreversible, so handle with caution.
  • The IF EXISTS clause prevents errors if the table is missing.
  • CASCADE can remove dependent objects, while RESTRICT requires manual removal of dependencies first.
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