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我正在使用PHP和MySQL。这是从四个不同的表中选择有关“user_1”的信息的最佳方法吗?我知道它是有效的,因为我已经尝试过了。但是,这是从“user_1”的多个表中选择信息的首选方法吗?从多个表中为PHP和MySQL选择一个唯一ID的信息
$query = "SELECT table_1.username, table_2.city, table_3.state, table_4.country
FROM table_1
JOIN table_2
ON table_1.username=table_2.username
JOIN table_3
ON table_1.username=table_3.username
JOIN table_4
ON table_1.username=table_4.username
WHERE table_1.username = 'user_1'";
你真的指'table_1.username = table_4.country'等吗? – cletus 2010-03-22 00:23:33
对不起。我的意思是table_1.username = table_2.username – Mark 2010-03-22 00:27:51