Can anyone expalin this FMS query?

Question

Dear Expert,
Can anyone expalin this FMS query, which follows
Query1:
IF $[ORDR.U_QuoOppNum] is NULL or $[ORDR.U_QuoOppNum] = ''
BEGIN
  SELECT  T0.Name  as 'Segments' 
     FROM [dbo].[@SEGMENT] T0
     Where SUBSTRING( T0.Code, 1, 3 ) = SUBSTRING( $[ORDR.U_QuoTypSeg], 1, 3)
END
ELSE
  SELECT T0.U_OppSeg FROM OOPR T0  where T0.OpprId = $[ORDR.U_QuoOppNum]
Query2:
SELECT  code
FROM [@SEGMENT] T0
Where SUBSTRING( T0.Code, 1, 3 ) = SUBSTRING( $[ORDR.U_QuoTypSeg], 1, 3)
AND Name = $[ORDR.U_QuoSeg]
Thanks in advance,
Dwarak

Answer 1

Dear Dwarak,
The 1st query assign UDF U_OppSeg value from Sales Opportunity to Sales order if U_QuoOppNum in sales order matches opportunity ID. Otherwise, assign Name value in UDT @SEGMENT where the first 3 letters match with sales order UDF U_QuoTypSeg.
The 2nd query is the first part of the previous query after IF. I explained in the 2nd half.
Thanks,
Gordon