Using Join to get data from multiple tables in SQL Server
If you only need to JOIN table A and B, but the configuration is on table C:

SELECT
    A.*,
    B.b1
FROM db.A
JOIN db.C ON (C.a_id=A.a_id)
JOIN db.B ON (B.b_id=C.b_id)
WHERE `table`.`field` = `parameter` # &lt;-- Aditional