SQL兩人在另一個表中一個表引用同一列的列

Question

我有這2個表

tbl_link 

    pID | fID_a | fID_b | link_desc 
    1 | 1 | 2 | aa + bb 

tbl_structure 

    pID | desc 
    1 | a 
    2 | b 

fID_a和fID_b外鍵爲PID在tbl_structure fID_a不允許NULL值，而fID_b確實

我想查詢結構時檢索結構2的遞減1

此刻我的SQL查詢看起來像這樣

SELECT a.link_desc, tbl_structure.desc FROM tbl_strukture 
LEFT JOIN tbl_link as a ON tbl_structure.pID = a.fID_a 
LEFT JOIN tbl_link as b ON tbl_structure.pID = b.fID_b 
WHERE tbl_structure.pID = 1 

但我只能得到與pID 1結構的desc！

感謝您的幫助！

Answer 1

你在找嗎？

SELECT l.link_desc, 
     s.[desc] description1, 
     s2.[desc] description2 
    FROM tbl_link l LEFT JOIN tbl_structure s 
    ON l.fID_a = s.pID LEFT JOIN tbl_structure s2 
    ON l.fID_b = s2.pID 
WHERE s.pID = 1 

SQLFiddle（SQL Server）的

SQLFiddle（MySQL的）