- What is difference between delete and drop?
- How do you truncate a table?
- Can we truncate a table with foreign key?
- What happens to indexes when you truncate a table?
- Which is faster truncate or drop table?
- Does truncate free space?
- How delete all data from a table?
- Is Grant DDL or DML?
- Is truncate faster than delete?
- Why truncate is DDL?
- What does it mean to truncate a table?
- Why use truncate instead of delete?
- Can we rollback truncate?
- Which command is used to delete the table?
What is difference between delete and drop?
DELETE is a Data Manipulation Language command, DML command and is used to remove tuples/records from a relation/table.
Whereas DROP is a Data Definition Language, DDL command and is used to remove named elements of schema like relations/table, constraints or entire schema..
How do you truncate a table?
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.
Can we truncate a table with foreign key?
3 Answers. You cannot truncate a table that has foreign key constraints. … Because TRUNCATE TABLE is a DDL command, it cannot check to see whether the records in the table are being referenced by a record in the child table.
What happens to indexes when you truncate a table?
When you truncate a table, Oracle Database automatically removes all data in the table’s indexes and any materialized view direct-path INSERT information held in association with the table. This information is independent of any materialized view log.
Which is faster truncate or drop table?
But TRUNCATE TABLE is faster and uses fewer system and transaction log resources than DELETE. The DELETE statement removes rows one at a time and records an entry in the transaction log for each deleted row. … In the SQL standard, DROP table removes the table and the table schema – TRUNCATE removes all rows.
Does truncate free space?
If there is data in the table you truncated then you shoul dbe able to run that script again and the free space will be higher. Free space does not affect the size of the data files – it means there will be more room in the file.
How delete all data from a table?
To delete every row in a table: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.
Is Grant DDL or DML?
Data definition language (DDL) statements let you to perform these tasks: Create, alter, and drop schema objects. Grant and revoke privileges and roles. Analyze information on a table, index, or cluster.
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.
Why truncate is DDL?
TRUNCATE resets the high water mark of the table, effectively eliminating all the previously existing rows. Treating it as a DDL statement allows it to be super-fast, as it allows it to function without retaining undo (rollback) information like DML statements.
What does it mean to truncate a table?
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 use truncate instead of delete?
TRUNCATE TABLE is faster and uses fewer system resources than DELETE , because DELETE scans the table to generate a count of rows that were affected then delete the rows one by one and records an entry in the database log for each deleted row, while TRUNCATE TABLE just delete all the rows without providing any …
Can we rollback truncate?
You cannot ROLLBACK TRUNCATE 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.
Which command is used to delete the table?
drop table commandThe drop table command is used to delete a table and all rows in the table. To delete an entire table including all of its rows, issue the drop table command followed by the tablename. drop table is different from deleting all of the records in the table.