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
``````

Standard syntax, duplicates retained

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

Alternate syntax 1, duplicates eliminated

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

Alternate syntax 2, duplicates retained

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

Help and Information

Getting SQL Server 2005 Assistance

Change History

Release History

17 July 2006

Changed content:
• Updated syntax and arguments to improve clarity.