Slide 9.13: SQL UPDATE statement

Slide 9.12: SQL DELETE FROM statement
Slide 9.14: SQL ALTER TABLE statement
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SQL UPDATE Statement

The UPDATE statement is used to update existing records in a table. Notice the where clause in the update syntax. The where clause specifies which record or records that should be updated.

If you omit the where clause, all records will be updated! Assume the person table is given below:

 UPDATE  table_name
   SET column1=value, column2=value2, ...
   WHERE some_column=some_value;

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		Storgt 67

 UPDATE  person  SET  first_name = 'Nina'
   WHERE  last_name = 'Rasmussen';
 UPDATE  person
   SET address = 'Nissestien 67', city = 'Sandnes';

The result tables from the above two updates are shown below:

The first update adds a first name to the person with a last name of “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
4	Rasmussen	Nina	Storgt 67

The second update is without a where clause. Thus, all records are updated.

person_id	last_name	first_name	address	city
1	Hansen	Ola	Nissestien 67	Sandnes
2	Svendson	Tove	Nissestien 67	Sandnes
3	Pettersen	Kari	Nissestien 67	Sandnes
4	Rasmussen	Nina	Nissestien 67	Sandnes

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