根据 WHERE 条件动态命名列

Question

目标：

我每周运行一次查询，并希望我的专栏中的一个返回带有前缀“W”的ISO_WEEK 号码。例如：W1。

更具体地说，我想将以下条件复制到列名中。

DATEPART(ISO_WEEK, table.login) = DATEPART(ISO_WEEK,GETDATE())-2

主要查询是：

 SELECT 
     CAST(t.log_time as Date)           AS Week1
    ,DATEPART(ISO_WEEK,t.log_time)      AS Week_Number -- Dynamically named with ISO_WEEK
    ,email                              AS Emails
 FROM table.memberlog as t
 WHERE 1=1
    AND DATEPART(ISO_WEEK, t.log_time) = DATEPART(ISO_WEEK,GETDATE())-2
    AND DATEPART(YEAR, t.log_time) = DATEPART(YEAR,GETDATE())

Answer 1

SQL Server 在设计上是声明性的，不支持宏替换。这样就可以使用动态 SQL，例如 ...

Declare @SQL varchar(max) = '
SELECT 
     CAST(t.log_time as Date)           AS Week1
    ,DATEPART(ISO_WEEK,t.log_time)      AS '+concat('W',DATEPART(ISO_WEEK,GETDATE())-2)+'
    ,email                              AS Emails
 FROM table.memberlog as t
 WHERE 1=1
    AND DATEPART(ISO_WEEK, t.log_time) = DATEPART(ISO_WEEK,GETDATE())-2
    AND DATEPART(YEAR, t.log_time) = DATEPART(YEAR,GETDATE())
'

Exec(@SQL)