Your question: What is truncate in MySQL?

What is the difference between TRUNCATE and delete in MySQL?

Unlike the DELETE command, the TRUNCATE command is fast. We cannot rollback the data after using the TRUNCATE command.

Difference between DELETE and TRUNCATE.

S.NO Delete Truncate
1. The DELETE command is used to delete specified rows(one or more). While this command is used to delete all the rows from a table.

What does TRUNCATE do?

TRUNCATE TABLE removes all rows from a table, but the table structure and its columns, constraints, indexes, and so on remain. To remove the table definition in addition to its data, use the DROP TABLE statement.

Why TRUNCATE is used in SQL?

TRUNCATE TABLE removes the data by deallocating the data pages used to store the table data and records only the page deallocations in the transaction log. Fewer locks are typically used. When the DELETE statement is executed using a row lock, each row in the table is locked for deletion.

What is the difference between TRUNCATE & Delete command?

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 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.

Is TRUNCATE faster than 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 .

How do you TRUNCATE a query?

The SQL TRUNCATE TABLE command is used to delete complete data from an existing table. You can also use DROP TABLE command to delete complete table but it would remove complete table structure form the database and you would need to re-create this table once again if you wish you store some data.

Is TRUNCATE a DDL or DML?

Although TRUNCATE TABLE is similar to DELETE , it is classified as a DDL statement rather than a DML statement. It differs from DELETE in the following ways: Truncate operations drop and re-create the table, which is much faster than deleting rows one by one, particularly for large tables.

How do you TRUNCATE a database?

Select Database -> More Database Operations -> Truncate Database (Shift+Del) to truncate (make the tables empty) all the tables of a database (however, the Tables and other objects (Stored Procedures, Views etc.)

What are 2 differences between delete and TRUNCATE?

Delete vs Truncate

SQL Delete SQL Truncate
It removes rows one at a time. It removes all rows in a table by deallocating the pages that are used to store the table data
It retains the identity and does not reset it to the seed value. Truncate command reset the identity to its seed value.
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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.

What is difference between stored procedure and function?

The function must return a value but in Stored Procedure it is optional. Even a procedure can return zero or n values. Functions can have only input parameters for it whereas Procedures can have input or output parameters. Functions can be called from Procedure whereas Procedures cannot be called from a Function.

How many rows can you insert into the table?

The number of rows that you can insert at a time is 1,000 rows using this form of the INSERT statement. If you want to insert more rows than that, you should consider using multiple INSERT statements, BULK INSERT or a derived table.

Are DML commands Autocommit?

No. Only the DDL(Data Definition Language )statements like create,alter,drop,truncate are auto commit.