MySQL查詢表連接

我有兩個表，遊戲和用戶設定了以下字段：MySQL查詢表連接

tblGAMES--> 
GAME_ID (int) primary key, 
P1_ID (int), 
P2_ID (int), 
P3_ID (int), 
P4_ID (int) 

tblUSERS--> 
USER_ID (int) primary key, 
FIRST_NAME (text), 
LAST_NAME (text)

我正在查詢我的數據庫，打印出每場比賽行的細節。例如：但

GAME_ID:1, P1:1, P2:2, P3:3, P4:4

不是打印出存儲在tblGAMES的ID我想打印出每個玩家的第一名稱出現的相應行中向tblUsers。這是可以使用單個查詢而不是多個查詢嗎？

end result-->GAME_ID:1, P1:David, P2:Paul, P3:John, P4:Bobby

來源

2011-12-27 user1118042

你需要加入用戶表4倍......

select g.GAME_ID, 
     u1.FIRST_NAME as ulname, 
     u2.FIRST_NAME as u2name, 
     u3.FIRST_NAME as u3name, 
     u4.FIRST_NAME as u4name 
from tblGAMES as g 
    left join tblUSERS as u1 on g.P1_ID =u1.USER_ID 
    left join tblUSERS as u2 on g.P2_ID =u2.USER_ID 
    left join tblUSERS as u3 on g.P3_ID =u3.USER_ID 
    left join tblUSERS as u4 on g.P4_ID =u4.USER_ID

（未經測試）

來源

2011-12-27 17:46:15 smp7d

在你將要tblUSERS每一次引用JOIN查詢。事情是這樣的：

SELECT 
    tblGAMES.GAME_ID, 
    tblUSER1.FIRST_NAME AS P1, 
    tblUSER2.FIRST_NAME AS P2, 
    tblUSER3.FIRST_NAME AS P3, 
    tblUSER4.FIRST_NAME AS P4 
FROM tblGAMES 
    INNER JOIN tblUSERS AS tblUSER1 ON tblGAMES.P1_ID = tblUSER1.USER_ID 
    INNER JOIN tblUSERS AS tblUSER2 ON tblGAMES.P2_ID = tblUSER2.USER_ID 
    INNER JOIN tblUSERS AS tblUSER3 ON tblGAMES.P3_ID = tblUSER3.USER_ID 
    INNER JOIN tblUSERS AS tblUSER4 ON tblGAMES.P4_ID = tblUSER4.USER_ID

請注意，我的語法可能需要一點調整，我沒有寫足夠的MySQL最近釋放，一方面它100％可靠。但你明白了。每個連接都被獨立地添加到整個產品中。

根據每個玩家的要求，您也可以更改JOIN類型。例如，如果某些遊戲是雙人遊戲，那麼您希望這些代碼是LEFT OUTER JOIN，以便更好地處理值爲null等。

來源

2011-12-27 17:47:52 David

MySQL查詢表連接

回答

相關問題