What does truncate mean in SQL?

SQL Truncate is a data definition language (DDL) command. It removes all rows in a table. SQL Server stores data of a table in the pages. The truncate command deletes rows by deallocating the pages. … At a high level, you can consider truncate command similar to a Delete command without a Where clause.

What is use of truncate in SQL?

The SQL TRUNCATE TABLE statement is used to remove all records from a table. It performs the same function as a DELETE statement without a WHERE clause. Warning: If you truncate a table, the TRUNCATE TABLE statement can not be rolled back in some databases.

What is difference between truncate and delete?

Key differences between DELETE and TRUNCATE

The DELETE statement is used when we want to remove some or all of the records from the table, while the TRUNCATE statement will delete entire rows from a table. DELETE is a DML command as it only modifies the table data, whereas the TRUNCATE is a DDL command.

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Why use truncate instead of delete?

TRUNCATE is faster than DELETE , as it doesn’t scan every record before removing it. TRUNCATE TABLE locks the whole table to remove data from a table; thus, this command also uses less transaction space than DELETE . Unlike DELETE , TRUNCATE does not return the number of rows deleted from the table.

Does truncate mean delete?

TRUNCATE is a DDL(Data Definition Language) command and is used to delete all the rows or tuples from a table. Unlike the DELETE command, the TRUNCATE command is fast. … We cannot roll back the data after using the TRUNCATE command.

How do I truncate a SQL database?

A solution that can TRUNCATE all tables

  1. Create a table variable to store the constraint drop and creation scripts for the database.
  2. Load the data for all tables in the database.
  3. Execute a cursor to drop all constraints.
  4. Truncate all tables.
  5. Recreate all the constraints.

What do you mean by truncate?

1 : to shorten by or as if by cutting off. 2 : to replace (an edge or corner of a crystal) by a plane.

What is the difference between truncate and DELETE in SQL?

SQL Truncate command places a table and page lock to remove all records. Delete command logs entry for each deleted row in the transaction log. The truncate command does not log entries for each deleted row in the transaction log. Delete command is slower than the Truncate command.

What is the difference between truncate and DROP in SQL?

1. The DROP command is used to remove table definition and its contents. Whereas the TRUNCATE command is used to delete all the rows from the table.

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Which is better DELETE or truncate?

Truncate removes all records and doesn’t fire triggers. Truncate is faster compared to delete as it makes less use of the transaction log. Truncate is not possible when a table is referenced by a Foreign Key or tables are used in replication or with indexed views.

Can DELETE be rolled back in SQL?

DROP and TRUNCATE are DDL commands, whereas DELETE is a DML command. DELETE operations can be rolled back (undone), while DROP and TRUNCATE operations cannot be rolled back.

Does TRUNCATE free space?

Truncating a table does not give any free space back to the disk – you need to run a SHRINKDATABASE operation for the allocated space to be successfully de-allocated and returned to the disk. Also, as others have mentioned, maybe the table was not taking up much space in the first place.

Can we rollback TRUNCATE in SQL Server?


Simply, you cannot rollback a transaction if it is already committed but you can do something else to get the data back (or at least some parts of it). When you execute the TRUNCATE statement, your data is still in the MDF file.

What is TRUNCATE in MySQL?

The TRUNCATE TABLE statement is used to remove all records from a table in MySQL. It performs the same function as a DELETE statement without a WHERE clause.

How can I get truncated data back in MySQL?

Basically, use mysqlbinlog to dump the contents of that log as a SQL script, then open that script in an editor and delete everything from the TRUNCATE statement to the end. See also https://dev.mysql.com/doc/refman/5.6/en/point-in-time-recovery.html for more tips on using mysqlbinlog for recovery.

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Do we need commit after TRUNCATE?

The TRUNCATE TABLE statement is a DDL command, so it includes an implicit COMMIT , so there is no way to issue a ROLLBACK if you decide you didn’t want to remove the rows.

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