嵌入在sum（）函数中的T-SQL IF语句

I'm attempting to convert a MySQL query to a T-SQL query and the IF statement that's enclosed within a SUM statement is tripping me up. Any suggestions?

我正在尝试将MySQL查询转换为T-SQL查询，并且包含在SUM语句中的IF语句正在绊倒我。有什么建议么？

SELECT
    CMTS_RQ.[Dated],
    CMTS_RQ.CMTS_Name,
    Count(CMTS_RQ.CMTS_Name) AS emat_count,
    Sum(if(CMTS_RQ.US_Pwr>=37 and CMTS_RQ.US_Pwr<=49)) AS us_pwr_good
FROM
    CMTS_RQ
GROUP BY
    CMTS_RQ.CMTS_Name,
    CMTS_RQ.[Dated]

But I get an error:

但是我收到一个错误：

Msg 156, Level 15, State 1, Line 5
Incorrect syntax near the keyword 'if'.
Msg 102, Level 15, State 1, Line 5
Incorrect syntax near ')'.

消息156，级别15，状态1，行5关键字“if”附近的语法不正确。消息102，级别15，状态1，行5'''附近的语法不正确。

1 个解决方案

#1

T-SQL doesn't have a "inline" IF statement - use a CASE instead:

T-SQL没有“内联”IF语句 - 使用CASE代替：

SELECT
    CMTS_RQ.[Dated],
    CMTS_RQ.CMTS_Name,
    Count(CMTS_RQ.CMTS_Name) AS emat_count,
    Sum(CASE 
           WHEN CMTS_RQ.US_Pwr >=37 AND CMTS_RQ.US_Pwr <= 49 
             THEN 1
             ELSE 0 
        END) AS us_pwr_good
FROM
    CMTS_RQ
GROUP BY
    CMTS_RQ.CMTS_Name,
    CMTS_RQ.[Dated]

So if the value of CMTS_RQ.US_Pwr is >= 37 AND <= 49 then add 1 to the SUM - otherwise 0. Does that give you what you're looking for?

因此，如果CMTS_RQ.US_Pwr的值> = 37 AND <= 49，则向SUM添加1 - 否则为0.这是否可以为您提供所需内容？

In SQL Server 2012 and newer, you can use the new IIF function:

在SQL Server 2012及更高版本中，您可以使用新的IIF功能：

SUM(IIF(CMTS_RQ.US_Pwr >= 37 AND CMTS_RQ.US_Pwr <= 49, 1, 0)) AS us_pwr_good

#1