How to check customer reference no. not being use more than once

Question

I have the following situation and appreciate if  some one could show me a simple solution.
“On the Sales order window, when user enter a value for Customer Ref. No”, check if the entered value has already  been used on any existing Sales Order, and give message eg. “this Ref. No already been used in SO. 257”
What is the easiest way of implementing the validation?
Using Formatted Search?
Triggers or Stored Procedure?
Or one must go about doing this simple task using SDK, DIAPI?
sample code illustrating solution would be much appreciated.
I tried to create a query and used it with Formatted search on the Field, but failed on an error.
the code using temporary hard coded value instead of $[$x.0.0] looks like this
if (SELECT    COUNT(*)
FROM         dbo.ORDR
WHERE     (NumAtCard = 'AAA' and CardCode ='1234')
) =0     
     Begin
                   select 'AAA' --redisplay value
     end
else
              begin
SELECT     TOP 1 'already used in SO '+ Convert(Char(3),DocEntry)
FROM        dbo.ORDR
WHERE     (NumAtCard = 'AAA')    
         end
where 'AAA' is the reference no. to check for customer '1234', this code works when I run it in SQL query analyser, but failed when I run it as query in Business one. the idea was to redisplay the entered No. 'AAA' if it is not found in any existing SO for cust ='1234'
can anyone point out what the error is or show  alternative code for the query.
thanks

Answer 1

Hi Andy,
I believe the best way to do this is probably to use the SDK as (to my knowledge) this is the only way you can get a message to be displayed and to stop the actual processing of the document.
If you want to go the formatted search route I would suggest you change your query a bit. I have played with your query and the following is an example as I got it working in SBO. I think SBO gets confused if there is more than one select statement that returns a result and I have started using variables to save the results of the select statements in.
[code]Declare @Val varchar(100)
declare @Count integer
set @Val = $[$14.0.0]
if (SELECT COUNT(*) FROM dbo.ORDR WHERE (NumAtCard = @Val and CardCode = $[$4.0.0])) > 0
begin
SELECT TOP 1 @Val = 'already used in SO '+ Convert(Char(3),DocEntry) FROM dbo.ORDR WHERE (NumAtCard = @Val)
end
select @Val[/code]
I hope it helps a bit,
Adele