为什么我收到此请求的错误“在预期条件的上下文中指定的非布尔类型”？

Question

我收到此错误：
"Error 102 : non-boolean type specified in a context where a condition is expected"
对于此请求：

DECLARE @num_dossiers TABLE (num_dossier INT,indice NVARCHAR(3))
insert into @num_dossiers
select num_dossier,indice from dossier where num_sec=57

delete from constitue where (num_dossier,indice) in select (num_dossier,indice) from @num_dossiers  

触发错误的请求是最后一个：

delete from constitue where (num_dossier,indice) in select (num_dossier,indice) from @num_dossiers   

导致此错误的原因可能是什么？

Answer 1

SQL Server 不支持多列 IN 子句（与 Oracle 不同）。

delete 
from constitue 
where (num_dossier,indice) in select (num_dossier,indice) from @num_dossiers 

这可以重写为 EXISTS：

DELETE c
FROM constitue c
WHERE EXISTS 
    (SELECT 1 FROM @num_dossiers nd WHERE n.num_dossier = c.num_dossier AND n.indice = c.indice);