我在将以下t-sql查询转换为DAX时遇到问题。
概述-有两个示例表-具有以下架构的Table1和Table2
表1(ID varchar(20),Name varchar(30))
表2(CapID varchar(20),CAPName varchar(30),CapID_Final varchar(20))
请注意:上述各表之间存在一对多的关系:表2中的[ID]与表1中的[CapID]
我正在尝试根据下面的t-SQL查询根据条件导出table2中的CapID_Final列,该列工作得很好-
SELECT CASE
WHEN [CapID] like 'CA%' and [CAPName]='x12345-Sample'
and [CapID] not in(select [ID] from Table1 where Name='x12345-Sample')
THEN 'Undefined_Cap_1'
WHEN [CapID] like 'CA%' and [CAPName]='z12345-Sample'
and [CapID] not in(select [ID] from Table1 where Name='z12345-Sample')
THEN 'Undefined_Cap_2'
WHEN [CapID] like 'CA%' and [CAPName]='a123-Sample'
and [CapID] not in(select [ID] from Table1 where Name='a123-Sample')
THEN 'Undefined'
ELSE [CapID]
END AS [CapID_Final] from Table2
但是,我希望在使用DAX的计算列中对Power BI中的CapID_Final列进行相同的推导。
到目前为止,我已经尝试了以下代码-但即使匹配的条件,它也会返回“未定义”-
CapID_Final =
IF(LEFT(Table2[CapID],2)="CA" && Table2[CAPName]="z12345-Sample" &&
NOT
(COUNTROWS (
FILTER (
Table1,CONTAINS(Table1,Table1[ID],Table2[CapID])
)
) > 0),"Undefined_Cap_1","Undefined"
)
我对DAX不熟悉,但是我尝试了一下,但无法弄清楚。 您能否让我知道如何将SQL查询转换为Power BI中的等效DAX?
答案 0 :(得分:1)
SWITCH
基本上等同于此处的CASE
子句:
CapID_Final =
SWITCH (
TRUE (),
LEFT ( Table2[CapID], 2 ) = "CA"
&& Table2[CAPName] = "x12345-Sample"
&& NOT (
Table2[CapID]
IN CALCULATETABLE ( VALUES ( Table1[ID] ), Table1[Name] = "x12345-Sample" )
), "Undefined_Cap_1",
LEFT ( Table2[CapID], 2 ) = "CA"
&& Table2[CAPName] = "z12345-Sample"
&& NOT (
Table2[CapID]
IN CALCULATETABLE ( VALUES ( Table1[ID] ), Table1[Name] = "z12345-Sample" )
), "Undefined_Cap_2",
LEFT ( Table2[CapID], 2 ) = "CA"
&& Table2[CAPName] = "a12345-Sample"
&& NOT (
Table2[CapID]
IN CALCULATETABLE ( VALUES ( Table1[ID] ), Table1[Name] = "a12345-Sample" )
), "Undefined",
Table1[CapID]
)
您甚至可以对其进行重构,以提高代码效率。假设我没有犯任何逻辑错误:
CapID_Final =
VAR IDs =
CALCULATETABLE ( VALUES ( Table1[ID] ), Table1[Name] = Table2[CAPName] )
RETURN
IF (
LEFT ( Table2[CapID], 2 ) = "CA"
&& NOT ( Table2[CapID] IN IDs ),
SWITCH (
Table2[CAPName],
"x12345-Sample", "Undefined_Cap_1",
"z12345-Sample", "Undefined_Cap_2",
"a12345-Sample", "Undefined"
),
Table1[CapID]
)
答案 1 :(得分:0)
作为最佳实践,请勿使用计算列。实际上,如果广泛使用它们,则会减慢您的模型刷新速度,并严重增加您的模型权重(因为它们未压缩)。而是在您的后端数据库或使用M Query计算它。
话虽如此,使用SWITCH函数可以很简单地解决您的问题:
SWITCH ( <Expression>, <Value>, <Result> [, <Value>, <Result> [, … ] ] [, <Else>] )
您的情况如下:
CapIDFinal:=
SWITCH(TRUE(),
AND(CONDITION_1_1, CONDITION_1_2), "Value if condition 1 is true",
AND(CONDITION_2_1, CONDITION_2_2), "Value if condition 2 is true",
"Value if none of above conditions is true
)