[英]MySQL - How do I achieve my desired output with LEFT JOIN?
以下查詢:
SELECT friendship.dom, friendship.sub,
user.id, user.fname, user.lname
FROM friendship
LEFT JOIN user ON friendship.dom = user.id
結果如下:
dom sub id fname lname
---------------------------
2 1 2 Seun Soti
1 2 1 Donal Lynch
但是我如何使輸出看起來像:
dom sub id_dom fname_dom lname_dom id_sub fname_sub lname_sub
----------------------------------------------------------------------
2 1 2 Seun Soti 1 Donal Lynch
1 2 1 Donal Lynch 2 Seun Soti
我只需要兩個用戶( dom
和sub
)都包括在輸出中。
這個怎么樣:
SELECT
f.dom, f.sub,
d.id dom_id, d.fname dom_fname, d.lname dom_lname,
s.id sub_id, s.fname sub_fname, s.lname sub_lname
FROM friendship f
LEFT JOIN user d ON f.dom = d.id
LEFT JOIN user s ON f.sub = s.id
嘗試這個:
SELECT friendship.dom, friendship.sub, user.id AS id_dom, ...
FROM friendship
LEFT JOIN user ON friendship.dom = user.id
那應該為您工作。 HTH
SELECT friendship.dom, friendship.sub,
user.id, user.fname, user.lname,
u1.id, u1.fname, u1.lname
FROM friendship
FROM friendship
LEFT JOIN user ON friendship.dom = user.id
LEFT JOIN user as u1 ON friendship.sub = u1.id
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