DBMS Truncate, Drop and Rename query ~ GNIITHELP

SQL queries to Truncate, Drop or Rename a Table

truncate command

truncate command removes all records from a table. But this command will not destroy the table's structure. When we apply truncate command on a table its Primary key is initialized. Following is its Syntax,

truncate table table-name

Here is an Example explaining it.

truncate table Student;

The above query will delete all the records of Student table.

truncate command is different from delete command. delete command will delete all the rows from a table whereas truncate command re-initializes a table(like a newly created table).

For eg. If you have a table with 10 rows and an auto_increment primary key, if you use delete command to delete all the rows, it will delete all the rows, but will not initialize the primary key, hence if you will insert any row after using delete command, the auto_increment primary key will start from 11. But in case of truncate command, primary key is re-initialized.

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drop command

drop query completely removes a table from database. This command will also destroy the table structure. Following is its Syntax,

drop table table-name

Here is an Example explaining it.

drop table Student;

The above query will delete the Student table completely. It can also be used on Databases. For Example, to drop a database,

 drop database Test;

The above query will drop a database named Test from the system.

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rename query

rename command is used to rename a table. Following is its Syntax,

rename table old-table-name to new-table-name

Here is an Example explaining it.

rename table Student to Student-record;

The above query will rename Student table to Student-record.