Friday, September 17, 2010

SQL UPDATE Statement

The UPDATE statement is used to update 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:





Now we want to update the person "Joshi, Pradnya" in the "Persons" table.

We use the following SQL statement:

UPDATE Persons
SET Address='Vile Parle', City='Mumbai'
WHERE LastName='Joshi' AND FirstName='Pradnya'


The "Persons" table will now look like this:



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='Vile Parle', City='Mumbai'


The "Persons" table would have looked like this:

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