EMS logo

Products Navigation

SQL Manager for MySQL

Our Partnership Status

Microsoft Certified Partner
Oracle Certified Partner
Embarcadero Technology Partner

EMS SQL Manager for MySQL

On-line Documentation

Truncate Tables


Truncate Table Wizard empties table(s) completely.

 

Logically, this is equivalent to a DELETE statement that deletes all rows, but there are practical differences under some circumstances.

 

In MySQL 3.23, TRUNCATE TABLE is mapped to COMMIT; DELETE FROM tbl_name, so it behaves like DELETE.

 

For InnoDB (before MySQL version 5.0.3), TRUNCATE TABLE is mapped to DELETE, so there is no difference. Starting with MySQL 5.0.3, fast TRUNCATE TABLE is available. The operation is still mapped to DELETE if there are foreign key constraints that reference the table.

 

For other storage engines, TRUNCATE TABLE differs from DELETE FROM in the following ways (since MySQL 4.0 and later):

  • truncate operations drop and recreate the table which is much faster than deleting rows one by one;
  • truncate operations are not transaction-safe; you get an error if you have an active transaction or an active table lock;
  • the number of deleted rows is not returned;
  • as long as the table definition file tbl_name.frm is valid, the table can be recreated as an empty table with TRUNCATE TABLE, even if the data or index files have become corrupted;
  • the table handler does not remember the last used AUTO_INCREMENT value, but starts counting from the beginning.

 

To run the wizard, select the Services | iconTruncateTables Truncate Tables... main menu item, or open a table in Table Editor and use the Truncate table item of the Navigation bar.

 

menuServices_TruncateTables

 

 

 

Availability:

Full version (for Windows)

Yes

Lite version (for Windows)

No

Note: To compare all features of the Full and the Lite versions of SQL Manager, refer to the Feature Matrix page.

 

 


See also:

Tables

Using templates