SQL DELETE

The DELETE command in SQL is used to remove existing records (rows) from a database table.

Whenever data is no longer required such as removing inactive users, outdated records, or incorrect entries the DELETE command is used.

Important: The DELETE command permanently removes data from table.

Understanding DELETE

A database table can be compared to a register or spreadsheet.

Using DELETE is similar to crossing out an entire row from a register.

Example: Students Table

Why Use the DELETE Command?

The DELETE command is used to

Syntax

DELETE FROM table_name
WHERE condition;

Deleting a Specific Record

DELETE FROM students
WHERE id = 3;

Result

Only the record with id = 3 is removed.

id	name	marks
1	Rahul	92
2	Anjali	90

Deleting Multiple Records Using a Condition

DELETE FROM students
WHERE marks < 90;

This removes all students whose marks are less than 90.

Deleting All Records from a Table

DELETE FROM students;

This deletes all rows from the table but keeps the table structure intact.

Difference Between DELETE and TRUNCATE

DELETE	TRUNCATE
Deletes selected rows	Deletes all rows
Supports WHERE clause	Does not support WHERE
Can be rolled back (in transactions)	Cannot be rolled back
Slower than TRUNCATE	Faster

Important Rules for Best Practices

Two Minute Dril