I need to write this query in self servicing.

select DESCRIPTION, min(TAXGROUPID) as TAXGROUPID, TAXGROUPSERIALNUMBER from TAXGROUP group by DESCRIPTION, TAXGROUPSERIALNUMBER

Suggest me.

For a custom resultSet you need a Dynamic List Then check how to use expressions on fields.

Finally you can add a Group By clause to fetch method.

From typedview how I can get group by clause ?

Why are you using a typedView? Are you using fields from a typedView?