DefaultMember (MDX)

Returns the default member of the specified dimension or hierarchy.

Parameters

Name	Type	Cardinality	Default value
	dimension-hierarchy-expression	one

Return

member

Description

Returns the default member for the specified dimension or hierarchy.

If a query does not define a hierarchy, its default members will be used:


        SELECT
        [Geography].[Geo].[United States] ON 0
        FROM
        [Sales]

This is equivalent to:


        SELECT
        [Geography].[Geo].[United States] ON 0
        FROM
        [Sales]
        WHERE
        ( [Geography].[Economy].defaultMember, [Time].[Calendar].defaultMember ... )

It is recommended, and very common, to define a hierarchy default member as the All member of the hierarchy.

Not using All members, may result in unexpected results.

For example defining a default member as [Geography].[Economy].[Canada] would make our first query returning an empty result. Why? Because the tuple ([Geography].[Geo].[United States],[Geography].[Economy].[Canada]) does not exits and is an empty tuple by construction.