Sorts a set and returns a subset from its higher-valued end, given a cutoff percentage that is applied to a total across set elements.
Example
First consider the following query and the results it returns:
SELECT MEASURES.[%COUNT] ON 0,
TOPPERCENT(birthd.decade.MEMBERS, 100, MEASURES.[%COUNT]) ON 1 FROM patients
Patient Count
1 2000s 157
2 1980s 155
3 1990s 144
4 1960s 136
5 1970s 128
6 1950s 107
7 1930s 56
8 1940s 54
9 2010s 44
10 1920s 13
11 1910s 6
Because percentage is 100, all members are returned.
Now consider a variation of the preceding, in which percentage is 50, so that we see the top 50 percent:
SELECT MEASURES.[%COUNT] ON 0, TOPPERCENT(birthd.decade.MEMBERS, 50, MEASURES.[%COUNT]) ON 1 FROM patients
Patient Count
1 2000s 157
2 1980s 155
3 1990s 144
4 1960s 136
The total for the %COUNT measure for these members is a little more than 50% of the total. (If the 1960s were omitted, the total count would be less than 50%.)