?️ MySQL DELETE

Quick Overview

The DELETE statement is used to remove existing records from a table in MySQL based on a given condition. Use it with caution — without a WHERE clause all rows will be removed.

Key Concepts

DELETE — command to remove rows from a table.
FROM — specifies which table to delete from.
WHERE — filters which rows should be deleted; essential to avoid full-table deletion.
TRUNCATE — faster alternative to remove all rows but not transactional.

Syntax / Theory

? View Code Example

-- Syntax for DELETE (preview before running)
DELETE FROM table_name WHERE condition;

Code Example(s)

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-- Delete a record from the 'students' table where the name is 'John Doe' (comment)
DELETE FROM students WHERE name = 'John Doe';

? View Code Example

-- Delete multiple records where the age is less than 18 (comment)
DELETE FROM students WHERE age < 18;

Live Output / Explanation

What happens when you run DELETE

Matching rows are removed immediately. If you need the ability to undo, perform deletes inside a transaction (if your storage engine supports it) so you can ROLLBACK if necessary. Always preview with SELECT first.

Example preview command:

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-- Preview rows that would be deleted to verify before deleting (comment)
SELECT * FROM students WHERE age < 18;

✅ Tips & Best Practices

Run a SELECT with the same WHERE clause before deleting to preview affected rows.
Wrap large deletes in transactions when possible so you can rollback if needed.
Use TRUNCATE to clear an entire table for performance, but note it's not transactional.
Back up important data before performing bulk deletions.

? Try It Yourself / Practice Tasks

Write a query to delete a student record with a specific id.
Delete all students from a specific city and preview with a SELECT first.
Practice wrapping a delete in a transaction (BEGIN; DELETE ...; ROLLBACK;) to observe rollback behavior.