SQL UPDATE

The SQL UPDATE general syntax looks like this:

UPDATE Table1 SET Column1 = Value1, Column2 = Value2

WHERE Some_Column = Some_Value

The SQL UPDATE clause changes the data in already existing database row(s) and usually we need to add a conditional SQL WHERE clause to our SQL UPDATE statement in order to specify which row(s) we intend to update.

If we want to update the Mr. Adam Red's date of birth to '5/10/1974' in our Company database table

FirstName	LastName	Email	DOB	Phone
Scott	Armstrong	Armstrong.yahoo.com	2/4/1968	887-676-2321
Adam	Red	red@himail.com	4/4/1978	792 343-2422
Santo	Harry	Harry@livingin.org	5/24/1978	416 323-3232
Jackson	Jimmy	Jimmy@supermail.co.uk	20/10/1980	416 323-8888

we need the following SQL UPDATE statement:

UPDATE Company

SET DOB = '5/10/1974'

WHERE LastName = 'Red' AND FirstName = 'Adam'

If we don’t specify a WHERE clause in the SQL expression above, all Company' DOB will be updated to '5/10/1974', so be careful with the SQL UPDATE command usage.

We can update several database table rows at once, by using the SQL WHERE clause in our UPDATE statement. For example if we want to change the phone number for all Company with last name Armstrong (we have 2 in our example Company table), we need to use the following SQL UPDATE statement:

UPDATE Company

SET Phone = '626 555-5555'

WHERE LastName = 'Armstrong'

After the execution of the UPDATE SQL expression above, the Company table will look as follows:

Now The Table will be updated with the new values or data.

MORE BASIC SQL COMMANDS