SQL UPDATE Statement


The UPDATE statement is used to update records in a table.


The UPDATE Statement

The UPDATE statement is used to update existing records in a table.

SQL UPDATE Syntax

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

Note: 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!


SQL UPDATE Example

The "Persons" table:

P_IdLastNameFirstNameAddressCity
1 Hansen Ola Timoteivn 10 Sandnes
2 Svendson Tove Borgvn 23 Sandnes
3 Pettersen Kari Storgt 20 Stavanger
4 Nilsen Johan Bakken 2 Stavanger
5 Tjessem Jakob    

Now we want to update the person "Tjessem, Jakob" in the "Persons" table.

We use the following SQL statement:

UPDATE Persons
SET Address='Nissestien 67', City='Sandnes'
WHERE LastName='Tjessem' AND FirstName='Jakob'

The "Persons" table will now look like this:

P_IdLastNameFirstNameAddressCity
1 Hansen Ola Timoteivn 10 Sandnes
2 Svendson Tove Borgvn 23 Sandnes
3 Pettersen Kari Storgt 20 Stavanger
4 Nilsen Johan Bakken 2 Stavanger
5 Tjessem Jakob Nissestien 67 Sandnes

 


SQL UPDATE Warning

Be careful when updating records. If we had omitted the WHERE clause in the example above, like this:

UPDATE Persons
SET Address='Nissestien 67', City='Sandnes'

The "Persons" table would have looked like this:

P_IdLastNameFirstNameAddressCity
1 Hansen Ola Nissestien 67 Sandnes
2 Svendson Tove Nissestien 67 Sandnes
3 Pettersen Kari Nissestien 67 Sandnes
4 Nilsen Johan Nissestien 67 Sandnes
5 Tjessem Jakob Nissestien 67 Sandnes