Slide 9.12: SQL DELETE FROM statement

Slide 9.11: Generating a primary key automatically (cont.)
Slide 9.13: SQL UPDATE statement
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SQL DELETE FROM Statement

The DELETE statement is used to delete existing records in a table. Notice the where clause in the delete syntax. The where clause specifies which records that should be deleted. If you omit the where clause, all records will be deleted!

Assume the person table is given below:

DELETE FROM  table-name [ WHERE  condition ];

SQL> DELETE FROM  student  WHERE  student_id = '2';

person_id	last_name	first_name	address	city
1	Hansen	Ola	Timoteivn 10	Sandnes
2	Svendson	Tove	Borgvn 23	Sandnes
3	Pettersen	Kari	Storgt 20	Stavanger
4	Rasmussen	Nina	Stien 12	Stavanger

 DELETE FROM  person  WHERE  last_name = 'Rasmussen';
 DELETE FROM  person;

The first delete statement deletes “Nina Rasmussen.”

person_id	last_name	first_name	address	city
1	Hansen	Ola	Timoteivn 10	Sandnes
2	Svendson	Tove	Borgvn 23	Sandnes
3	Pettersen	Kari	Storgt 20	Stavanger

The second delete statement deletes all rows in the person table without deleting the table. This means that the table structure, attributes, and indexes will be intact.

person_id	last_name	first_name	address	city

Demonstration
Below is an SQL test area from W3Schools, which uses the well-known Northwind sample database. The tables here are for read only because of the problem of embedding the scripts. For a fully working example, check this by using Chrome.

Result:

The Database includes:

Tablename	Record
Customers	91
Categories	8
Employees	10
OrderDetails	518
Orders	196
Products	77
Shippers	3
Suppliers	29

W3C WebSQL

WebSQL Browser Support