Mysql：从另一个中减去一列的数据[关闭]

I would like to subtract one column of data from another, namely gdded from gppy; both are stored in a MySQL database.

Here is my code but it seems there is something wrong. I've searched anywhere but I cannot find the right answer.

My script below

INSERT INTO denmrk 
(EMPID, NAME, DATE_FR, DATE_TO, Tangkay, Alis, gppy, gdded , NET_PAY, SSS_comboE, IBG_EMPLYE, PROCESSED_DATE)
VALUES
(6666, 'JUAN DELACRUZ', '2014-02-01 00:00:00', '2014-02-01 00:00:00', 'BBBB CO', 'DRIVER', 3383.04, 300, gppy- gdded , 150, 150, GETDATE() );

With the given code and implied database structure, how can I can achieve this?

BTW there is no need to store the manipulated result in the database. You can do this when you are select the data from the database. SO it would be better to drop that col and the idea to store the calc result in the database as well.