MySQL SET IF Statement

Can someone show me the correct mysql syntax to do the following:

Update a column in a table with 1 of 3 values:

If col_A = 4 set col_Z to col_A If col_B = 4 set col_Z to col_B E开发者_如何学Clse set col_Z to NULL (or leave alone because col_Z is initialized to NULL)

Here's what I have:

Update my_table
SET col_Z = IF(col_A = 4, col_A, IF(col_B = 4, col_B, NULL))
WHERE id = "001"

IS this correct?

Yes, it looks correct.

The following code will be simpler though.

UPDATE my_table
SET col_Z = IF(col_A = 4 OR col_B = 4, 4, NULL)
WHERE id = "001"