SELECT AS问题

Question

我尝试执行以下查询：

SELECT t1.[user1], t1.[user2],
    (CAST(t1.[total_event_duration] AS DECIMAL)) / (CAST (t2.[total_events_duration] AS DECIMAL)) AS buddy_strength 
FROM [CDRs].[dbo].[aggregate_monthly_events] AS t1 
INNER JOIN [CDRs].[dbo].[user_monthly_stats] AS t2 
    ON t1.[user1] = t2.[user1]  
WHERE buddy_strength > 0.02

但它返回错误“无效的列名'buddy_strength'”

有谁知道如何修复上面的查询？

Answer 1

SELECT * 
FROM
    (
    SELECT
        t1.[user1], t1.[user2],(CAST(t1.[total_event_duration] AS DECIMAL))/(CAST (t2.[total_events_duration] AS DECIMAL)) AS buddy_strength 
        FROM [CDRs].[dbo].[aggregate_monthly_events] AS t1 
            INNER JOIN [CDRs].[dbo].[user_monthly_stats] AS t2 
                ON t1.[user1] = t2.[user1]  


   ) foo
        WHERE foo.buddy_strength > 0.02

Answer 2

您不能在WHERE子句中使用别名。您需要重复整个表达式（CAST(t1.[total_event_duration] AS DECIMAL))/(CAST (t2.[total_events_duration] AS DECIMAL)>0.02）。

Answer 3

您不能在where，group by或having子句中使用别名。您可以通过将其包装在子查询中来解决这个问题：

SELECT * FROM (
    SELECT
        t1.[user1],
        t1.[user2],
        (CAST(t1.[total_event_duration] AS DECIMAL))
            / (CAST (t2.[total_events_duration] AS DECIMAL))
            AS buddy_strength
    FROM [CDRs].[dbo].[aggregate_monthly_events] AS t1
    INNER JOIN [CDRs].[dbo].[user_monthly_stats] AS t2 ON t1.[user1] = t2.[user1]
) a
WHERE a.buddy_strength > 0.02

否则你将不得不再次输入整件事，这是不好的。

Answer 4

您不能在where子句中使用别名列。我认为你必须在where子句中重现该派生字段的值，如下所示：

SELECT t1.[user1], t1.[user2],(CAST(t1.[total_event_duration] AS DECIMAL))/(CAST (t2.[total_events_duration] AS DECIMAL)) AS buddy_strength 
    FROM [CDRs].[dbo].[aggregate_monthly_events] AS t1 
        INNER JOIN [CDRs].[dbo].[user_monthly_stats] AS t2 
            ON t1.[user1] = t2.[user1]  
    WHERE (CAST(t1.[total_event_duration] AS DECIMAL))/(CAST (t2.[total_events_duration] AS DECIMAL)) > 0.02