Head

The MDX Head function for Essbase returns the first n members or tuples present in a set.

Syntax

Head ( set [,numeric value expression ] )

Parameters

set

The set from which to take items.

numeric value expression

The count of items to take from the beginning of the set. If omitted, the default is 1. If less than 1, an empty set is returned. If the value exceeds the number of tuples in the input set, the original set is returned.

Example

Example 1

This example uses the following part of the Sample Basic outline:

The following expression

[Product].children

returns the set:

{ [100], [200], [300], [400], [Diet] }

Therefore, the following expression

 Head (
  [Product].children, 2) 

returns the first two members of the previous result set:

{ [100], [200] }

Example 2

This example uses the following parts of the Sample Basic outline:

The following expression

 CrossJoin ( [100].children, [South].children )

returns the set:

{ ([100-10], Texas), ([100-10], Oklahoma), ([100-10], Louisiana), ([100-10], [New Mexico]),
  ([100-20], Texas), ([100-20], Oklahoma), ([100-20], Louisiana), ([100-20], [New Mexico]),
  ([100-30], Texas), ([100-30], Oklahoma), ([100-30], Louisiana), ([100-30], [New Mexico]) }

And the following expression

Head ( CrossJoin ([100].children, [South].children), 8 )

returns the first 8 tuples of the previous result set:

{ ([100-10], Texas), ([100-10], Oklahoma), ([100-10], Louisiana), ([100-10], [New Mexico]),
  ([100-20], Texas), ([100-20], Oklahoma), ([100-20], Louisiana), ([100-20], [New Mexico]) } 

Additionally, the following expression

([Year].generations(2).members)

returns the set of members comprising the second generation of the Year dimension:

{ [Qtr1], [Qtr2], [Qtr3], [Qtr4] }

Therefore, the following query

SELECT
  {([Year].generations(2).members)}
ON COLUMNS,
Head (
 CrossJoin (
  [100].children, [South].children), 8
     ) 
ON ROWS
FROM Sample.Basic 

returns the grid:

Table 4-76 Output Grid from MDX Example

(axis)		Qtr1	Qtr2	Qtr3	Qtr4
100–10	Texas	489	536	653	547
	Oklahoma	87	92	128	211
	Louisiana	93	106	128	137
	New Mexico	76	101	122	70
100–20	Texas	206	199	152	82
	Oklahoma	84	66	55	79
	Louisiana	119	158	171	104
	New Mexico	–103	–60	–98	–18

See Also

Tail