Below are MySQL tables. I need to insert values from table A's ID column to Table B's ID_A column. Already existed values in ID_A should be ignored. So that in the below mentioned example IDs 1 to 3 from Table A should be ignored and IDs 4 to 10 should be inserted in table B. ID_X's value is constant i.e. 3.
What would be a single insert SQL query?
One straightforward option is to left join
B and insert only those records from
A which do not already appear in
INSERT INTO B (ID_A, ID_X) SELECT A.ID, 3 FROM A LEFT JOIN B ON A.ID = B.ID_A WHERE B.ID_A IS NULL