MySQL外连接与连接表具有多个表的依赖关系

Question

I have 3 tables A, B and T

T holds a foreign key to table A and B respectively.

Now I would like to get all rows of (A,B,T) even if T is empty.

SELECT * from

A
LEFT OUTER JOIN T t1 ON t1.A_ID = A.id,
B
LEFT OUTER JOIN T t2 ON t2.B_ID = B.id

WHERE A.B_ID = B.ID

Now the problem is that I get too many rows so I add the following:

AND t1.id = t2.id

But now I get no rows at all which I tried to avoid in the first place via including the LEFT OUTER JOIN.

EDIT: Apart from any sample-data or table-layout my question is merely if a table T with foreign-key-dependencies to more than ONE table in this case A + B needs 2 left-outer-joins as given above or maybe there is another way?

Simply refering to table A in the second left-join like some users suggested cannot work as it is out-of-scope, also explained here
So it works if you surround both tables with parens:

SELECT * from (A, B)
LEFT OUTER JOIN T t ON t.A_ID = A.id and t.B_ID = B.id

Answer 1

Try

select *
from A
join B on A.B_ID = B.ID
left join T on T.A_ID = a.id and T.B_ID = b.id

.. assuming I've understood your question correctly, and you intend a regular, inner join between A and B

Answer 2

Try this query: If A and B no any relation:

SELECT * FROM
(A, B)
LEFT OUTER JOIN T ON T.A_ID = A.id
AND T.B_ID = B.id

And if A and B have relation add this line at last:

WHERE A.B_ID = B.ID

Answer 3

If I've understood right, then maybe this will work for you?

SELECT * from
A
LEFT OUTER JOIN T t1 ON t1.A_ID = A.id,
B
LEFT OUTER JOIN T t2 ON (t2.B_ID = B.id AND t1.id = t2.id)

WHERE A.B_ID = B.ID