Properties of a dataitem (For Ex, Aggregate, Roll up Aggregate)

[venkynet]

Hi all,

I'm new to Cognos. In our project we are using Cognos 8.2 BI tool for reporting purpose. Can anybody pls explain me with examples, the difference between Aggregate and Roll up Aggregate property of a dataitem ? I mean when and at wat situations to assign the property of a dataitem as TOTAL, SUMMARIZE, CALCULATED etc..

Please explain me with examples..

Thanks in advance.

[MFGF]

Hi,

The first key point to realize is that a Cognos 8 query will automatically group and aggregate detail data rows from the underlying data source.  For example, if you have a table containing a million order rows for ten distinct products, and you select just the Product Name and Quantity fields from this, your query will return ten rows of data in the result - one for each distinct Product Name - and the Quantity value for each will be aggregated from the rows in the underlying table.  The type of aggregation is controlled by the Aggregate property of the Quantity item.

If you were then to add in another descriptive item such as Order Year, and use the Group button in the report to group your rows based on this, you would also have the opportunity to add aggregate footers at the end of each Year group to aggregate Quantity values for each year.  The type of aggregation in this situation is controlled by the Roll up Aggregate property.

Regards,

MF.

[venkynet]

Hi MFGF..

Thanks alot for ur reply. It helped me to some extent. But i have another doubt... In the second part of your explaination, u told about adding another descriptive item such as Order Year, and using the Group button in the report to group rows based on that..
My doubt is that if we add Order Year to the report then cognos will automatically group by on Order Year also as u said while explaining the Aggregate property. So what is the need of using Group button in the report ?
And also pls explain me the difference between Total and Summarize in the Aggregate property..

Regards
Venk

[mvjcognos]

Aggregate: This will use for detail level
Rollup Aggregate: This will use for summarized level like total level

Total: Use this when u are calculating measure u want total for particular unique id's

Calculate: Use this when u r calculating a calculated measure