Question

I have three tables, I don’t know if they all need to be used, but basically I need Table A and Table C to be compared, if there is an ID that is in Table A that is not in Table C, then in Table C the ID is to be added along with value in another cell in that row. See below for an example:

Original Table A:

-------------------------
Sku | Status
-------------------------
ABC | Enabled
DEF | Enabled
GHI | Enabled
JKL | Disabled
MNO | Enabled

Original Table C:

-------------------------
Sku | Status
-------------------------
ABC | Enabled
DEF | Enabled
GHI | Enabled

After Query Table C:

-------------------------
Sku | Status
-------------------------
ABC | Enabled
DEF | Enabled
GHI | Enabled
JKL | Disabled
MNO | Disabled

Answer 1

This will work in MySQL:

INSERT INTO b 
SELECT * 
FROM a 
WHERE 
  NOT EXISTS 
     (SELECT * FROM b WHERE b.sku = a.sku);