union-mdx.md

title	description	author	ms.author	ms.reviewer	ms.date	ms.service	ms.subservice	ms.topic	ms.custom
Union (MDX)	Union (MDX)	kfollis	kfollis	kfollis	02/17/2022	sql	analysis-services	reference	mdx

Union (MDX)

Returns a set that is generated by the union of two sets, optionally retaining duplicate members.

Syntax

  
Standard syntax  
Union(Set_Expression1, Set_Expression2 [,...n][, ALL])  
  
Alternate syntax 1  
Set_Expression1 + Set_Expression2 [+...n]  
  
Alternate syntax 2  
{Set_Expression1 , Set_Expression2 [,...n]}  

Arguments

Set Expression 1
A valid Multidimensional Expressions (MDX) expression that returns a set.

Set Expression 2
A valid Multidimensional Expressions (MDX) expression that returns a set.

Remarks

This function returns the union of two or more specified sets. With the standard syntax and with alternate syntax 1, duplicates are eliminated by default. With the standard syntax, using the ALL flag keeps duplicates in the joined set. Duplicates are deleted from the tail of the set. With alternate syntax 2, duplicates are always retained.

Examples

The following examples demonstrate the behavior of the Union function using each syntax.

Standard syntax, duplicates eliminated

SELECT Union   
   ([Date].[Calendar Year].children  
   , {[Date].[Calendar Year].[CY 2002]}  
   , {[Date].[Calendar Year].[CY 2003]}  
   ) ON 0  
FROM [Adventure Works]  
  

Standard syntax, duplicates retained

SELECT Union   
   ([Date].[Calendar Year].children  
   , {[Date].[Calendar Year].[CY 2002]}  
   , {[Date].[Calendar Year].[CY 2003]}  
   , ALL  
   ) ON 0  
FROM [Adventure Works]  
  

Alternate syntax 1, duplicates eliminated

SELECT   
   [Date].[Calendar Year].children   
   + {[Date].[Calendar Year].[CY 2002]}   
   + {[Date].[Calendar Year].[CY 2003]} ON 0  
FROM [Adventure Works]  
  

Alternate syntax 2, duplicates retained

SELECT   
   {[Date].[Calendar Year].children  
   , [Date].[Calendar Year].[CY 2002]  
   , [Date].[Calendar Year].[CY 2003]} ON 0  
FROM [Adventure Works]  
  

See Also

+ (Union) (MDX)
MDX Function Reference (MDX)