sql - select中子查询语句的where子句

Question

假设我有一个这样的查询:

   Select col1, 
          col2, 
          (select count(smthng) from table2) as 'records'
   from table1

我想将它过滤为“记录”列不为空。

我不能做到这一点:

         Select col1, 
                col2, 
               (select count(smthng) from table2) as 'records'
          from table1
        where records is not null  

我想出的最好方法是将此结果集写入表值参数，并对该结果集进行单独查询。有任何想法吗？

Answer 1

只需将其移至派生查询即可。您不能在 WHERE 子句中使用在 SELECT 子句中定义的列。

Select col1, col2, records
from
(
    Select col1, 
           col2, 
           (select ..... from table2) as records
    from table1
) X
where records is not null;