如何只执行一次“IN”子查询

Question

我的SQL Server查询速度很慢：

SELECT Style
FROM Storage
WHERE Style NOT IN (SELECT ValidStyle FROM ValidStyles)

此语法导致SELECT ValidStyle FROM ValidStyles对父查询的每一行执行一次。我怎样才能重写这个以仅运行子查询一次？

Answer 1

SELECT Style 
FROM Storage s
WHERE NOT EXISTS(SELECT * FROM ValidStyles vs WHERE vs.ValidStyle=s.Style)

Answer 2

我只是在这里猜一下，但这应该有用......

 SELECT S.Style 
 FROM Storage S 
 LEFT OUTER JOIN ValidStyles vs on S.Style = VS.ValidStyle
 WHERE vs.ValidStyle is null

Answer 3

SELECT Style
FROM Storage S
LEFT JOIN ValidStyles VS
ON
 S.Style = VS.ValidStyle
WHERE VS.ValidStyle IS NULL