Re: CHAIN Versus SETLL and READ When Data Needed

Why not something like this:

  C           clear                RecordFirmat
  C     Key3  chain  file
  C           if     not %found
  C           exsr   NotFoundSR
  C           else
   * at this point the record fields have values.
  C     key2  chain  file
  C           if     %found
  C     key1  chain  file
  C           endif
  c           endif
  c           endif

That is clear, fast, and accurate.


Shannon O'Donnell wrote:

I posed this question on MCPressOnline the other day but I would like to
get more opinions on it so I'll post it here too.   A shop-standard
hangs in the balance.

   Assume that you have an RPG program that has logic such that you need
to first see if some data is in a file, based on a key, and then if so,
you do something with that data.

Further assume that this file has a complex key with three fields.

    The program logic is such that you check the maximum number of keys
for a match down to the minimum number of keys

     Like this:

              Key1    Klist

                          Kfld              Fld1

                          Kfld              Fld2

                          Kfld              Fld3

              Key2     Klist

                          Kfld              Fld1

                          Kfld              Fld2

              Key3     Klist

                           Kfld             Fld1

   Which one of these logic blocks is most efficient?

   Key1   Setll   file

       If    %FOUND(file)

               Key1   READE file

                       Use Fields

       Else

          Key2    Setll  File

            If   %FOUND(file)

                     Key2 Use Fields

           Else

             Key3  Setll File

                  If   %FOUND(file)

                     Key3 READE file

               Endif

            Endif

          Endif

OR....

               KEY1  Chain file

                          If       %FOUND(file)

                              Use fields

                         Else

              KEY2   Chain  file

                          If      %FOUND(file)

                              Use Fields

                          Else

              KEY3   Chain file

                          If   %FOUND(file)

                             Use Fields

                         Endif

                         Endif

                         Endif

My opinion is that the CHAIN is more efficient from both a
coding/maintenance standpoint and from an I/O standpoint, but I'm open
to opinions.