Kenhuang Academy
  • English

      • PostgreSQL DELETE

      Overview

      The DELETE statement removes rows from a table. This chapter covers how to delete specific rows and use conditions.

      Basic DELETE

      -- Delete single row
DELETE FROM users WHERE id = 1;

-- Delete multiple rows
DELETE FROM users WHERE status = 'inactive' AND last_login < '2022-01-01';

      DELETE with RETURNING

      -- Return deleted values
DELETE FROM users WHERE id = 1
RETURNING id, name, deleted_at;

      DELETE with USING

      -- Delete using another table
DELETE FROM orders USING users 
WHERE orders.user_id = users.id 
AND users.status = 'banned';

      TRUNCATE TABLE

      -- Faster than DELETE for all rows
TRUNCATE TABLE logs;

-- Reset auto-increment sequences
TRUNCATE TABLE logs RESTART IDENTITY;

-- Cascade to dependent tables
TRUNCATE TABLE logs CASCADE;

      Summary

      DELETE key points:

      • Use WHERE clause to specify rows to delete
      • Use RETURNING clause to get deleted values
      • Use TRUNCATE for faster table clearing