RE: Astonished by embedded sql

It seems to me that this is the equivalent of opening myfile for each
subroutine call, reading every record in the file then closing the

file

again.

Yes, that's right.

Although I'm not sure about the reading. Is the whole file read at

the

open cursor statement?

No, but it is read in its entirety at the DoU loop. (FETCH does the
lifting.)

Myfile has a couple of hundred records. For the whole primary file

only

about 10 different values for someDateField will be used.

Well, that does seem strange, and the program *may* enjoy significant
performance improvement if myfile is made to be the driver. Or by a
completely different approach. But not sure since we only see a small
part
of the picture.

By the way, I didn't think FETCH into *qualified* DS did quite what we
would
hope. Perhaps I am mistaken on that.

Dennis Lovelady
http://www.linkedin.com/in/dennislovelady
--
Nobody can outstubborn your mother.

I don't understand the use of this embedded sql instead of using a
CHAIN operation. Hopefully someone will explain.

A file is read by the RPG cycle (primary file) and the subroutine is
called for every record of the file.
This file contains a couple of hundred thousand records.

It seems to me that this is the equivalent of opening myfile for each
subroutine call, reading every record in the file then closing the

file

again.
Although I'm not sure about the reading. Is the whole file read at

the

open cursor statement?

Myfile has a couple of hundred records. For the whole primary file

only

about 10 different values for someDateField will be used.


D MyFile_DS E DS EXTNAME (myfile) QUALIFIED

Begsr mysr

wSql = 'Select * From myfile '+
'Where myfield = ''' + %Char(someDateField) + ''' ';

Exec SQL
Prepare S2 From :wSql;

If SqlCod < 0;
//Treat error
EndIf;

Exec SQL
Declare C2 Cursor For S2;

Exec SQL
Open C2;

If SqlCod < 0;
//Treat error
EndIf;

DoU SqlCod <> 0;
Exec SQL
Fetch Next from C2 Into :MyFile_DS;
Leave;

EndDo;

Exec SQL
Close C2;

EndSr;