How does TRUNCATE work 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.
How do I TRUNCATE a specific record in SQL?
TRUNCATE cannot be executed with a WHERE clause means that all records will be removed from the TRUNCATE / statement. However, partitions can be truncated as shown in the below T-SQL statement. From the above statement, partitions 2,4,6,7,8 will be truncated leaving the other partitions data will not be truncated.
How do you empty a table in SQL?
Deleting data from tables
- Use the DELETE statement without specifying a WHERE clause. With segmented table spaces, deleting all rows of a table is very fast. …
- Use the TRUNCATE statement. The TRUNCATE statement can provide the following advantages over a DELETE statement: …
- Use the DROP TABLE statement.
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 command?
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.
Can we use where in TRUNCATE?
The truncate command removes all rows of a table. We cannot use a Where clause in this. It is a DDL command. … The truncate command does not log entries for each deleted row in the transaction log.
Why 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 . Unlike DELETE , TRUNCATE does not return the number of rows deleted from the table.
What is delete command in SQL?
In the database structured query language (SQL), the DELETE statement removes one or more records from a table. A subset may be defined for deletion using a condition, otherwise all records are removed.
Can you truncate a column in SQL?
What is the Truncate Command in SQL? We use the Truncate command to delete the data stored in the table. The working of truncate command is similar to the working of Delete command without a where clause.
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.
Can we TRUNCATE database?
In order to truncate all tables in your database you must first remove all the foreign key constraints, truncate the tables, and then restore all the constraints. … Load the data for all tables in the database. Execute a cursor to drop all constraints. Truncate all tables.
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.