How to create roll-ups in Informix SQL? - sql

Question

I often meet in different reports intermediate roll-ups like this:
|calltypename |rating |number |
+-----------------+----------------------------------------+-------+
|sales |1.0 |1 |
|sales |5.0 |2 |
| |3.666666666666666666666666666667 |3 |
|service |1.0 |1 |
|service |3.0 |1 |
|service |5.0 |3 |
|service |9.0 |1 |
| |4.666666666666666666666666666667 |6 |
Here records are grouped by calltypename with intermediate roll-ups:
average rating and sum of numbers.
Informix SQL have no ROLLUP operator, so I'm trying to achieve similar result with UNION:
select calltypename, TO_NUMBER(datavalue) as rating, count(*) as number
from calldata
where datakey="qrate1"
group by calltypename, rating
union all
select calltypename, AVG(TO_NUMBER(datavalue)) as rating, count(*) as number
from calldata
where datakey="qrate1"
group by calltypename
order by calltypename, rating
It produces the following result:
|calltypename |rating |number |
+-----------------+----------------------------------------+-------+
|sales |1.0 |1 |
|sales |3.666666666666666666666666666667 |3 |
|sales |5.0 |2 |
|service |1.0 |1 |
|service |3.0 |1 |
|service |4.666666666666666666666666666667 |6 |
|service |5.0 |3 |
|service |9.0 |1 |
Is there any hint how to order the records so that roll-ups will always take their place below the related group?
After some time, I have found a solution that I do not like very much. Idea is to add a fake column "ROLLUP" that will be used in ORDER BY statement:
select calltypename as queue, "" as rollup,
datavalue as rating, count(*) as number
from calldata
where datakey="qrate1"
group by queue, rating
union all
select calltypename as queue, "rollup" as rollup,
TO_CHAR(AVG(TO_NUMBER(datavalue)),"*.*") as rating, count(*) as number
from calldata
where datakey="qrate1"
group by queue
order by queue, rollup, rating
This produce a result:
|queue |rollup |rating|number |
+-------+----------+------+-------+
|sales | |1 |1 |
|sales | |5 |2 |
|sales |rollup |3.7 |3 |
|service| |1 |1 |
|service| |3 |1 |
|service| |5 |3 |
|service| |9 |1 |
|service|rollup |4.7 |6 |
But I would like it without ROLLUP column...