🚰 SQL TRUNCATE TABLE – Quickly Delete All Rows from a Table
Introduction – What is SQL TRUNCATE TABLE?
The TRUNCATE TABLE command in SQL is used to delete all rows from a table efficiently, while preserving the table’s structure, columns, and constraints. It’s often faster than DELETE and used for quick, irreversible cleanups.
In this guide, you’ll learn:
- Syntax and behavior of
TRUNCATE TABLE - Differences between
DELETE,DROP, andTRUNCATE - Performance implications and best use cases
1. TRUNCATE TABLE Syntax
TRUNCATE TABLE table_name;
Instantly removes all rows from the table.
2. TRUNCATE vs DELETE vs DROP
| Command | Deletes Data | Keeps Structure | Rollback Support | Affects Identity (Autoinc) |
|---|---|---|---|---|
DELETE | (if in transaction) | |||
TRUNCATE | (some DBMS) | (resets counter) | ||
DROP TABLE |
3. Example – Truncate a Log Table
TRUNCATE TABLE audit_logs;
Clears all records from audit_logs but keeps table definition intact.
4. Behavior Notes
- Cannot truncate a table referenced by foreign key constraints
- Often faster than
DELETEbecause it bypasses row-by-row logging - May reset IDENTITY/AUTOINCREMENT fields depending on DBMS
- Not always rollback-safe (e.g., MySQL autocommit mode)
Best Practices
| Recommended | Avoid This |
|---|---|
| Use for temp or staging table cleanup | Truncating tables with foreign keys |
| Test on a copy before production execution | Assuming rollback is possible |
| Pair with backup in live environments | Using in audit or production tables |
Summary – Recap & Next Steps
TRUNCATE TABLE is a quick and efficient method to remove all records from a table. It’s best for non-critical, non-referenced tables where full deletion is required.
Key Takeaways:
- TRUNCATE is faster and cleaner than DELETE
- Keeps table structure, drops only the data
- May reset IDENTITY and bypass transactions
Real-World Relevance:
Used in staging environments, ETL pipelines, testing frameworks, and log cleaning routines.
Next: Learn DROP TABLE to remove table structures or DELETE for selective row deletions.
FAQ – SQL TRUNCATE TABLE
Does TRUNCATE remove the table?
No. It removes all rows but keeps the table structure intact.
Can I roll back a TRUNCATE?
Depends on DBMS. PostgreSQL supports it in transactions. MySQL may not.
Can I truncate a table with a foreign key?
No. Most DBMS prevent it unless the key is dropped or disabled.
Does TRUNCATE reset identity values?
Yes, in SQL Server and PostgreSQL. MySQL depends on engine configuration.
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