(One table) insert rows

Question

This question is the continuation of this one.

I have the following table egr:

+---------+------------+
|  offid  |  groupid   |
+---------+         


        

Answer 1

This may be easier to achieve using the except operator:

INSERT INTO egr (offid, groupid)
SELECT 2, groupid
FROM   egr
WHERE  offid = 1
EXCEPT
SELECT 2, groupid
FROM   egr
WHERE  offid = 2