I need help with a VB function

mainrotor
mainrotor used Ask the Experts™
on
Hi Experts,
I have a report that takes too long to generate.  Below is the fuctions that generates the report.
How can I update my function to speed it?
Could I use a static variable to speed it up?
Should I use Temp tables?

Sub Main()
   dim dt as datatable = "select * from orders,items where orders.itemid = item.itemid and invdate between Jan and Dec"
   for each dr as datarow in dt.rows
      call ProcFunc(dr)
   next dr
end sub
 
Sub ProcFunc(dr as datarow)
   dim dtProc as datatable = "select * from bigtable, itemdetail where bigtable.itemid = itemdetail.itemid and location = " & dr!location
   for each drSlowProc in dtProc.rows
       dim Cost as decimal = CalcLanded(dr!cost, drSlowProc!duty, dr!location)
       dim dtThis as datatable = "select * from hugetable where location = " & dr!location & " and Cost between 10 and 20"
       call OtherFunc(Cost, drThis)
   next drSlowProc
end sub

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Thank you in advance,
mrotor
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ChloesDad

Commented:
Any process that has nested searches is going to be slow. Can you show us what you are trying to generate as this will allow us to perhaps come up with a better solution.
Qlemo"Batchelor", Developer and EE Topic Advisor
Top Expert 2015

Commented:
Using repetive SQL calls to get data is almost always a costly operation, because of the overhead involved for each SQL call.
So the first try is to make it a single SQL getting all data as required. And only the data required, that is you should restrict the columns to retrieve to allow for SQL, disk I/O, network I/O and memory optimization.

Also, in ProcFunc you are calling the SQL for hugetable in a loop though it does not have any changing parameters. You need to run that SQL only once per DR record, so move it infront of the FOR loop.
Top Expert 2014
Commented:
Please try this.
Sub ProcFunc(dr as datarow)
   dim Cost as decimal
   dim dtThis as datatable
   dim dtProc as datatable = "select * from bigtable, itemdetail where bigtable.itemid = itemdetail.itemid and location = " & dr!location
   for each drSlowProc in dtProc.rows
       Cost = CalcLanded(dr!cost, drSlowProc!duty, dr!location)
       dtThis = "select * from hugetable where location = " & dr!location & " and Cost between 10 and 20"
       call OtherFunc(Cost, drThis)
   next drSlowProc
end sub

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plusone3055

Commented:
the other thing you can do is Index the tables that you are calling to in SQL serer to Optimize the Query

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