How to update field to add value to existing value?

Question

How to update field to add value to existing value?
For example I have

Table name: table

id   credit
1      4
2      5
3      3
         


        

Answer 1

This is just a simple UPDATE. Try the following.

UPDATE tableName
SET Credit = Credit + 7
WHERE ID = 1

note that ID = 1 and ID = '1' is the same as the server automatically parses it.