mysql - 三重嵌套 mysql select 在应该返回结果时没有返回结果

Question

此 SQL 查询

(SELECT * FROM OperatorRoster as roster 
    INNER JOIN ( SELECT *, count(*) as activeSlots FROM Connectors
    group by (operator)) as connectors
ON connectors.operator = roster.operator)

工作正常并返回我需要的所有值，但我需要在新查询中使用结果

但是如果我尝试使用它:

SELECT * FROM (SELECT * FROM OperatorRoster as roster 
    INNER JOIN ( SELECT *, count(*) as activeSlots FROM Connectors
    group by (operator)) as connectors
ON connectors.operator = roster.operator) as q

它什么也不返回。 我如何查询这个子查询？

Answer 1

您缺少主连接的 ON 子句。

  on q.___= Operators.___