表A name user owner
machine1 1 2 machine2 3 4 表B userid username 1 aaa 2 bbb 3 ccc 4 ddd 以上两个表,表A 设备的用户id和所有者id,表B是用户id对应的名称如何用sql语句显示为下面的表显示为 name user ower
machine1 aaa bbb machine2 ccc dddsql:
SELECT name, user=(SELECT username FROM B WHERE B.userid = A.user), owner=(SELECT username FROM B WHERE B.userid = A.owner)FROM A
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