Re: Emulating SQL "SELECT DISTINCT" with LF?

Hi

I don't think there is anything you can do using LFs.

I do suggest something like this to skip duplicates - this assumes that your key contains the fields in the DISTINCT column list.

SETLL *LOVAL (or *START?)
READ
DOW NOT *EOF
SETGT using key values of record just READ
IF NOT *EOF
READ
ENDIF
ENDDO

This is probably not quite right, the idea is to skip over everything with the same value efficiently, using the access path of the file.

HTH
Vern

On 6/26/2020 6:52 AM, Patrik Schindler wrote:

Hello,

is it possible with the facilities available through logical files to have some flavour of READ of that particular LF return the next record with a non-equal key? Like the opposite of READE, maybe?

Or must I solve that programmatically (roughly):
SETLL to *LOVAL,
Loop:
READE until EOF,
READ
if EOF, continue
goto Loop.

Also, I dimly remember there were some "group facilities" available with the good old RPG cycle (which even I want to omit). I can't recall to have read about something helpful in the RPGLE Docs.

:wq! PoC

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