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Explain the difference between DELETE and TRUNCATE.

Parthiban Kannan
Updated on December 2, 2025

2 min read

The main difference between DELETE and TRUNCATE in SQL lies in how they remove data and how they impact performance, logging, and rollback behavior.

DELETE is a DML (Data Manipulation Language) command that removes rows one by one from a table based on a condition. You can use a WHERE clause to delete specific rows, and it logs each deleted row in the transaction log. Because of that, DELETE operations are slower for large tables but give more control.

For example:

🗃️
filename.sql 
DELETE FROM Employees WHERE DepartmentID = 5;

This deletes only employees from department 5, keeping the rest of the table intact.

TRUNCATE, on the other hand, is a DDL (Data Definition Language) command that removes all rows from a table instantly. It doesn’t log individual row deletions — instead, it deallocates all the data pages used by the table. So, it’s much faster than DELETE but can’t include a WHERE clause.

Example:

🗃️
filename.sql 
TRUNCATE TABLE Employees;

This removes all data from the table but keeps the structure (columns, constraints, etc.) intact.

I applied this in a data refresh process where staging tables were loaded daily. Since those tables were completely replaced each time, I used TRUNCATE instead of DELETE — it cleared millions of rows in seconds and reduced transaction log size.

One challenge I faced was when TRUNCATE couldn’t be used because the table had foreign key constraints — it will fail unless those constraints are removed or disabled first.

Key differences at a glance:

  • DELETE can remove specific rows (WHERE supported); TRUNCATE removes all rows.
  • DELETE logs each row deletion; TRUNCATE logs only page deallocation.
  • DELETE can activate triggers; TRUNCATE cannot.
  • DELETE can be rolled back if inside a transaction; TRUNCATE also can, but only if explicitly wrapped in one.
  • TRUNCATE resets identity columns to their seed value; DELETE doesn’t.

An alternative in some cases is using DROP TABLE when you don’t even need the table structure anymore — but usually, TRUNCATE is the best choice when you just want a clean slate with high performance.

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