What is the difference between delete and truncate and drop in SQL?

What is difference between DELETE and DROP?

DELETE command is a Data Manipulation Language command whereas, DROP is a Data Definition Language Command. The point that distinguishes DELETE and DROP command is that DELETE is used to remove tuples from a table and DROP is used to remove entire schema, table, domain or constraints from the database.

Which is faster DELETE or TRUNCATE?

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 .

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.

What is DROP and delete in SQL?

The DROP command removes a table from the database. All the tables’ rows, indexes, and privileges will also be removed. … 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.

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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 a key difference between TRUNCATE and DELETE?

Delete vs Truncate

SQL Delete SQL Truncate
Delete command is slower than the Truncate command. It is faster than the delete command.
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

Why is TRUNCATE table faster than delete?

Delete table is a logged operation. So the deletion of each row gets logged in the transaction log, which makes it slow. Truncate table also deletes all the rows in a table, but it won’t log the deletion of each row instead it logs the deallocation of the data pages of the table, which makes it faster.

Why TRUNCATE is DDL and Delete is DML?

Truncate reinitializes the identity by making changes in data definition therefore it is DDL, whereas Delete only delete the records from the table and doesn’t make any changes in its Definition that’s why it is DML.

How do I rollback a delete in SQL?

Following is an example, which would delete those records from the table which have the age = 25 and then ROLLBACK the changes in the database. SQL> DELETE FROM CUSTOMERS WHERE AGE = 25; SQL> ROLLBACK; Thus, the delete operation would not impact the table and the SELECT statement would produce the following result.

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Is update a DDL command?

DDL is Data Definition Language which is used to define data structures.

Difference between DDL and DML:

Basic command present in DDL are CREATE, DROP, RENAME, ALTER etc. BASIC command present in DML are UPDATE, INSERT, MERGE etc.

What is the difference between DROP and DELETE in mysql?

DROP is used to remove tables (and databases). DELETE is used to delete rows from tables.