Question

i am trying to write a procedure that inserts rows into a temp table. the basis of the table is an insurance policy table listing the amount of the premium earned over the life of the policys. the original data consists of the trans_date (date sold) and the policy_start and policy_end dates. i.e. if the policy is 12 months long, we give each month 1/12 of the premium collected.

so something like

while trans_month < policy_end month

insert to tblUEPtmp
select dateadd(mm, 1, trans_date), earned_premium from tblpolicys

set trans_date = dateadd(mm, 1, trans_date)

(i know this is rubbush code but i completely baffled at the moment)

My problem is that i need to create the extra 11 rows of data and modify the transaction date to add 1 month each time until the modified transaction date = policy_end date.

i’ve researched using a CTE, but while loops aren’t posible within a CTE..

is this something a multistatement table function could do?

Many thanks.

Answer 1

You can defo do this with a CTE, for example this little snippet will demonstrate how to do recursion using dates:

declare @start DATETIME = '2012-02-01'
declare @end DATETIME = '2013-02-01'
;with cte (date)
AS
(
    SELECT @start
    UNION ALL
    SELECT DATEADD(mm,1,cte.date)
    FROM cte WHERE DATEADD(mm,1,cte.date)<@end
)
select * from cte

That will generate a list of dates between @start & @end with month gaps.

You can

1. Use your real tables in place of the dummy dates
2. Perform an insert into...select ... from cte to insert your required data

If you can provide more detail about your table schema, I can probably help out with a more concrete example.