Question

Let’s say i have two fields a and b.

Now let’s say i want to write a query which would update if a = 100 AND b = 120 else it would create new field.

Also a and b have to be unique to each other, what i mean is that it can be two a equals to 100 or two b equals to 200, but there can’t be more fields like

a = 100 and b = 120, i hope you get what i mean.

Answer 1

If you have a UNIQUE constraint on the (a,b) combination, you can use the INSERT ... ON DUPLICATE KEY UPDATE ... syntax for this functionality. Examples:

INSERT INTO TableX
  ( a, b, c, d, e)
VALUES
  ( 100, 200, 1, 2, 3)
ON DUPLICATE KEY UPDATE
  c = VALUES(c)
, d = VALUES(d)
, e = VALUES(e)

INSERT INTO TableX
  ( a, b, c, d, e)
VALUES
  ( 100, 200, 1, 7, 20)
ON DUPLICATE KEY UPDATE
  c = c + 1
, d = d + 1
, e = e + 1