SQL Server：有没有办法从聚合函数中选择别名列？

Question

所以我有这些列来自执行聚合函数： Table

SELECT MachineName,

       (100*((1)
       -((
       sum(CASE p1.CounterName
             WHEN 'Available Bytes' THEN
               p2.CounterValue
             ELSE
               0
           END)
       /NULLIF(
       (sum(CASE p1.CounterName
              WHEN 'Available Bytes' THEN
                p2.CounterValue
              ELSE
                0
            END)
        +
        sum(CASE p1.CounterName
              WHEN 'Committed Bytes' THEN
                p2.CounterValue
              ELSE
                0
            END)
        +
        sum(CASE p1.CounterName
              WHEN 'Modified Page List Bytes' THEN
                p2.CounterValue
              ELSE
                0
            END)),0) ))))  As Memory

我只想要需要选择的 Memory > 75，但我对 SQL 和聚合函数不够熟悉，所以我不确定这是否可能。

Answer 1

您可以尝试使用如下子查询 -

select * from 
(
SELECT MachineName,

       (100*((1)
       -((
       sum(CASE p1.CounterName
             WHEN 'Available Bytes' THEN
               p2.CounterValue
             ELSE
               0
           END)
       /NULLIF(
       (sum(CASE p1.CounterName
              WHEN 'Available Bytes' THEN
                p2.CounterValue
              ELSE
                0
            END)
        +
        sum(CASE p1.CounterName
              WHEN 'Committed Bytes' THEN
                p2.CounterValue
              ELSE
                0
            END)
        +
        sum(CASE p1.CounterName
              WHEN 'Modified Page List Bytes' THEN
                p2.CounterValue
              ELSE
                0
            END)),0) ))))  As Memory
)A where memory>75