Example
TRUNCATE tableName;
This will delete all the data and reset AUTO_INCREMENT index. It's much faster than DELETE FROM tableName on a huge dataset. It can be very useful during development/testing.
When you truncate a table SQL server doesn't delete the data, it drops the table and recreates it, thereby deallocating the pages so there is a chance to recover the truncated data before the pages where overwritten. (The space cannot immediately be recouped for innodb_file_per_table=OFF.)
