MySQL:LEFT JOIN 中的子查询

Question

我有一个问题。我想在 LEFT JOIN .. ON

中使用子查询 tm

SELECT t.*, 
    (SELECT `uid` FROM `truck_transport` tm WHERE tm.from = t.station ORDER BY RAND() LIMIT 1) as tm 
FROM `truck_trailer` t 
LEFT JOIN `truck_transport` tm2 ON (tm2.uid = tm) ...

如果我在 FROM 中使用子查询，rand 的结果始终是相同的。

抱歉我的语言:/

Answer 1

试试这个

SELECT t.*, tm.uid
FROM `truck_trailer` t 
    LEFT JOIN (SELECT `uid` FROM `truck_transport` ORDER BY RAND() LIMIT 1) as tm 
    ON (tm.uid = t.station)