SQL: windowed aggregate functions for DB2 iSeries

Question

Is count not a valid aggregation function for row partitions for SQL DB2 on the iSeries?

This query works:

select ROW_NUMBER() over (partition by COL1, COL2 order by COL3 asc)
from MyTable

And this query gives a syntax error:

select COUNT(1) over (partition by COL1, COL2)
from MyTable

The error message is pointing at the parenthesis before the word partition:

[Message SQL0401] Token ( is not a valid token. A partial list of valid tokens is , FROM INTO.

I'm aware I can rewrite the query to avoid the row partition, but I'd like to know why this isn't working.

Answer 1

No, COUNT() is not the same type of function as ROW_NUMBER().

If you want the number of rows per (col1,col2) then you could simply use

select COL1, COL2, count(*)
  from MyTable
  group by col1, col2