DAX相当于包含联合、假列和别名的sql语句

Question

我想写一个PowerBI DAX表达式，有:一)联盟B)列的别名C) dummy column

在SQL中我这样写:

select distinct bill_lvl_1 as unique_values, "bill_lvl_1" as source from main_table
union
select distinct bill_lvl_2 as unique_values, "bill_lvl_2" as source from main_table;

如何使用DAX表达式?

Answer 1

VAR values1 =    
SELECTCOLUMNS(
VALUES(main_table)
,"unique_values", 'main_table'[bill_lvl_1 ])
)
VAR values1AndDummy =
ADDCOLUMNS(
values1
,"source","bill_lvl_1"
VAR values2 = ...
VAR values2AndDummy = ...

RETURN 
UNION(values1AndDummy,values2AndDummy)