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Like Denis, most of our files are defined using DDS.  But that's packaged 
software for you.
I define my new files using SQL.  Then again, I am probably the only one.

Here's something to chew over:

Problem with DDS created files.  DDS created files are built to allow crap 

in most fields.  Some legacy thing when people got off grunting, thumping 
their chest and writing batch programs that checked fields down to the 
byte level for data that is right.  Like the first COBOL program I wrote 
in a class - make sure a field that is supposed to be numeric, is.  DDS 
files are fast to write to, but slow to read from because they don't care 
what kind of data you write to them.  But they'll check the data quality 
on a read.  When you think about it, most of your data access is reading, 
right?
SQL created files check data on a write.  Not on a read.
Recently saw a classic example of this.
Compile this:
                R JOEPR
                  MYCHAR         5A
                  MYPACK         9P 2 
with CRTPF FILE(ROB/JOEP) SRCFILE(ROB/QDDSSRC)
Run this command:  CRTPF FILE(ROB/JOEP2) RCDLEN(10)
STRSQL
INSERT INTO ROB/JOEP2 VALUES('NOWISTHETI')

CREATE TABLE ROB/JOEP3 
(MYCHAR CHAR (5 ) NOT NULL WITH DEFAULT, 
 MYPACK DEC (9 , 2) NOT NULL WITH DEFAULT)
RCDFMT JOEP3R
(exit sql)

CPYF FROMFILE(JOEP2) TOFILE(JOEP) MBROPT(*ADD) FMTOPT(*NOCHK)
Notice:  Allowed crap into JOEP.  You have a packed decimal field with 
alpha characters in it.

But CPYF FROMFILE(JOEP2) TOFILE(JOEP3) MBROPT(*ADD) FMTOPT(*NOCHK)
Tells me to bugger off with CPF5035-Data mapping error on member JOEP3.

Now if I attempt to read the corrupted DDS created file with a simple 
RPGLE cycle program
     FJOEP      IP   E             DISK
     FQSYSPRT   O    F   80        PRINTER
     OQSYSPRT   D
     O                       MYCHAR
     O                                              ' '
     O                       MYPACK 
I will get RNQ0907-Decimal-data error occurred.

Verifying that DDS files check data integrity on read.  SQL created files 
check data integrity on write.

Rob Berendt

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