MySQL两个独立的表，它们的联接在第三个表中不存在

Question

I have three tables A (Master), B (Master) and C (Transaction). The combination of A.id and B.id exists in C. I want that data of A where combination of A.id and B.id do not exist in table C.

I tried the following but get no rows selected.

SELECT A.* from A, B, C where A.id != C.id and B.id != C.id

I am not that good at creating queries.

Can someone please form a query for this?

Answer 1

SELECT * 
FROM A 
WHERE A.id NOT IN (
    SELECT Aid FROM C)

Your question is a bit strange though, this query selects all the id's of A which are not in table C.

Answer 2

SELECT A.*, B.* 
FROM A , B
WHERE A.id = B.id AND A.id NOT IN (SELECT Aid FROM C) AND B.id NOT IN (SELECT Bid FROM C)

Answer 3

SELECT * FROM A，C B.id = A.id上的左联接B B.id = C.id上的左联接B在A.id = C.id和B.id为NULL的情况下