加入两个Mysql表来获取多列的名称

Question

我试图根据表中的member_id,parent_id和sponsor_id表从表“member”中提取parent_name和sponsor_name。

我试过下面的查询，但我不知道为什么它不起作用。

SELECT mt.member_id, mt.parent_id, mt.sponsor_id, mt.member_name, m.member_name as parent_name , m1.member_name as sponsor_name 
FROM `member_tree` mt 
LEFT JOIN `member` m ON mt.parent_id = m.member_id 
LEFT JOIN `member` m1 ON mt.sponsor_id = m1.member_id 
WHERE mt.`member_id` IN (1000015,1000016,1000017,1000018,1000019,1000020,1000021,1000022,1000023,1000024,1000025,1000026,1000027,1000028,1000029,1000030) 

谢谢。

Answer 1

此查询工作正常，你可以检查它在小提琴http://sqlfiddle.com/#!2/499e95/1

只要确保

你有没有在这两个表MEMBER_NAME领域，因为你已经写mt.member_name和MT是指到member_tree表

如果你没有在member_tree标签成员名称le从小提琴使用此查询http://sqlfiddle.com/#!2/5d2bd/1

SELECT mt.member_id, mt.parent_id, mt.sponsor_id, m.member_name, 
m1.member_name as parent_name , m2.member_name as sponsor_name 
FROM `member_tree` mt 
LEFT JOIN 
`member` m ON mt.member_id = m.member_id 
LEFT JOIN 
`member` m1 ON mt.parent_id = m1.member_id 
LEFT JOIN 
`member` m2 ON mt.sponsor_id = m2.member_id 
WHERE mt.`member_id` 
IN (1000015,1000016,1000017,1000018,1000019,1000020,1000021,1000022,1000023,1000024,1000025,100 0026,1000027,1000028,1000029,1000030) 

Answer 2

对我来说看起来不错 - 尽管我可能会这样写。

Answer 3

您能否确保parent_id和sponsor_id存在外键。如果不是，您可以检查member_ids 1000007到1000014是否存在于成员表中。