SQL - DROP Table

The SQL DROP TABLE statement is a Data Definition Language (DDL) command that is used to remove a table s definition, and its data, indexes, triggers, constraints and permission specifications (if any).

Note −

You should be very careful while using this command because once a table is deleted then all the information available in that table will also be lost forever.

To drop a table in a database, one must require ALTER permission on the said table and CONTROL permissions on the table schema.

Even though is a data definition language command, it is different from TRUNCATE TABLE statement as the DROP statement completely frees the table from the memory.

Syntax

The basic syntax of this DROP TABLE statement is as follows −

DROP TABLE table_name;

Example

Let us first verify the CUSTOMERS table and then we will delete it from the database as shown below −

EXEC sp_help CUSTOMERS;
+---------+---------------+------+-----+---------+-------+
| Field   | Type          | Null | Key | Default | Extra |
+---------+---------------+------+-----+---------+-------+
| ID      | int(11)       | NO   | PRI |         |       |
| NAME    | varchar(20)   | NO   |     |         |       |
| AGE     | int(11)       | NO   |     |         |       |
| ADDRESS | char(25)      | YES  |     | NULL    |       |
| SALARY  | decimal(18,2) | YES  |     | NULL    |       |
+---------+---------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

This means that the CUSTOMERS table is available in the database, so let us now drop it as shown below.

DROP TABLE CUSTOMERS;

Output

The output is displayed as follows −

(0 rows affected)

Verification

Now, to verify if the table is actually dropped, you can use the EXEC sp_help command as shown −

EXEC sp_help CUSTOMERS;

Following error is displayed −

ERROR 1146 (42S02): Table  TEST.CUSTOMERS  doesn t exist

Here, TEST is the database name which we are using for our examples.

The IF EXISTS clause

Instead of always checking if the table exists or not in a database before dropping it, you can use the IF EXISTS clause in the DROP TABLE statement.

This clause, when specified in the DROP TABLE query, will automatically check whether the table exists in the current database and then drops it, if yes. If the table does not exist in the database, the query will be ignored.

Syntax

Following is the basic syntax of DROP TABLE IF EXISTS −

DROP TABLE [IF EXISTS] table_name;

Example

If you try to drop a table that doesn’t exist in the database, without using the IF EXISTS clause, as shown below −

DROP TABLE demo;

An error will be generated −

ERROR 1051 (42S02): Unknown table  sample.demo 
If you use the IF EXISTS clause along with the DROP TABLE statement as shown below, the specified table will be dropped and if a table with the given name, doesn’t exist the query will be ignored.

But if you try to drop a table that does not exist in a database, using the IF EXISTS clause, as shown below −

DROP TABLE IF EXISTS demo;

The query will be ignored with the following output displayed −

Query OK, 0 rows affected, 1 warning (0.10 sec)