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. ... DROP is DDL.

1. What is the difference between delete and drop in mysql?
2. What is difference between delete truncate and drop?
3. What are 2 differences between delete and truncate?
4. Does dropping a database delete it?
5. Why use truncate instead of delete?
6. Which is better truncate or delete?
7. What is the difference between where and having clause?
8. What will happen if you use Delete command without the where clause?
9. Why truncate is DDL?
10. Why delete can be rollback but truncate not?
11. Can we rollback delete and truncate?
12. What are the DML commands?

What is the difference between delete and drop in mysql?

Delete is used to remove the rows, while drop is used to remove the tables and DB. delete - removes the rows from the table - where clause can be used to delete specific rows. ... drop - removes a table from the database. - rows, indexes and privileges will also be removed.

What is difference between delete truncate and drop?

DROP statement is a Data Definition Language(DDL) Command which is used to delete existing database objects. Unlike TRUNCATE which only deletes the data of the tables, the DROP command deletes the data of the table as well as removes the entire schema/structure of the table from the database. ...

What are 2 differences between delete and truncate?

Delete vs Truncate

Does dropping a database delete it?

Dropping a database deletes the database from an instance of SQL Server and deletes the physical disk files used by the database. If the database or any one of its files is offline when it is dropped, the disk files are not deleted. These files can be deleted manually by using Windows Explorer.

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 ...

Which is better truncate or delete?

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 the difference between where and having clause?

Difference between WHERE and HAVING clause

The WHERE clause is used in the selection of rows according to given conditions whereas the HAVING clause is used in column operations and is applied to aggregated rows or groups. If GROUP BY is used then it is executed after the WHERE clause is executed in the query.

What will happen if you use Delete command without the where clause?

Delete Query in SQL should always be executed with the WHERE clause to avoid unwanted data loss. Delete statement without WHERE clause will delete all the records of the table and without proper rollback mechanism, your data could be lost forever.

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.

Why delete can be rollback but truncate not?

In case of DELETE, SQL Server removes all the rows from table and records them in Log file in case it is needed to rollback in future. ... If deallocated data files are overwritten by other data it can be recovered using rollback. There is no guarantee of the rollback in case of TRUNCATE.

Can we rollback delete and truncate?

The operation cannot be rolled back. 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.

What are the DML commands?

Some commands of DML are:

• SELECT – retrieve data from the a database.
• INSERT – insert data into a table.
• UPDATE – updates existing data within a table.
• DELETE – deletes all records from a table, the space for the records remain.
• MERGE – UPSERT operation (insert or update)
• CALL – call a PL/SQL or Java subprogram.