7.06 – Update and Delete

Computer Science Revision

You can change the fields of existing records using UPDATE ... SET ... WHERE.

Example 1 shows a use of the UPDATE command.

Example 1
UPDATE Students
SET DateOfBirth = 04/12/2008
WHERE StudentID = 1226

Note that the = symbol can mean two different things: in a WHERE clause, it checks if two things are equal, but in a SET clause, it changes the value of a field.

SQL also allows us to delete records from a table using DELETE FROM ... WHERE.

Example 2 shows a use of the DELETE FROM command.

Example 1
DELETE FROM Students
WHERE StudentID = 1228

Use the UPDATE command to subtract 1 from the StudentID of all records where it is greater than 1227.

Tap/click to reveal UPDATE Students
SET StudentID = StudentID - 1
WHERE StudentID > 1227