Subqueries are not allowed in this context. Only scalar expressions are allowed.

我想获取表中某一列的最大值，然后插入到另外一个表中，报错的Sql如下：

insert into AA(AA_ID,AA_YWFSRQ) 
values
(NewID(),(  SELECT   CONVERT(varchar, DATEADD(day,- 1, CAST(SUBSTRING(MAX(YEB_RQ), 1, 4) 
                                    + SUBSTRING(MAX(YEB_RQ), 5, 2) + SUBSTRING(MAX(YEB_RQ), 7, 2) 
                                     AS datetime)), 112) FROM      YEB ));

insert into AA(AA_ID,AA_YWFSRQ) 
select
NewID(),(  SELECT   CONVERT(varchar, DATEADD(day,- 1, CAST(SUBSTRING(MAX(YEB_RQ), 1, 4) 
                                    + SUBSTRING(MAX(YEB_RQ), 5, 2) + SUBSTRING(MAX(YEB_RQ), 7, 2) 
                                     AS datetime)), 112) FROM      YEB )

==》在此上下文中不允许使用子查询。只允许使用标量表达式。