Head (MDX)

Returns the first numeric number of elements from the set.

In our example, returns the two first members of the set.

Query

Head([Geography].[Geo].[Continent].Members,2)

Result

{ 
  [Geography].[Geo].[Continent].[America], 
  [Geography].[Geo].[Continent].[Europe]
}

Assertion : MDX Equals

{[Geography].[Geo].[Continent].Members(0),[Geography].[Geo].[Continent].Members(1)}

Returns the first element from the set.

Query

Head([Geography].[Geo].[Continent].Members)

Result

{ 
  [Geography].[Geo].[Continent].[America]
}

Assertion : MDX Equals

Head([Geography].[Geo].[Continent].Members,1)

If the number of elements requested is greater than the number of elements in the set, the original set is returned.

Query

Head([Geography].[Geo].[Continent].Members,300000000)

Result

{ 
  [Geography].[Geo].[Continent].[America], 
  [Geography].[Geo].[Continent].[Europe]
}

Assertion : MDX Equals

{[Geography].[Geo].[Continent].Members}

Returns an empty set if applied to a NULL entity.

Query

Head(NULL,2)

Result

{}

Assertion : MDX Equals

Head( [Geography].[Geo].[Continent].Members, 0)

Assertion : MDX Equals

Head( [Geography].[Geo].[Continent].Members, -1)

Returns an error if applied to an invalid type.

Query

Head([Geography].[Geo].[Continent].Members, "hello")

Result

Error Code    : OLAP_FUNCTION_ARGUMENT_TYPE_MISMATCH
Error Message : Head() : argument (1) type mismatch: expected:'numeric', got:'string'