RE: E: Logical File or OPNQRYF or anyother way ?

I don't think so, but if you used CPYSPLF to a flat file, that would be
an example.

I'm wondering if the difference in terms relates to (IIRC) that one can
only access data in a truly relational database management system
through the use of SQL. Seems that was one of Codd's Laws?

> -------- Original Message --------
> Subject: Re: E: Logical File or OPNQRYF or anyother way ?
> From: "Booth Martin" <booth@xxxxxxxxxxxx>
> Date: Mon, March 07, 2005 4:22 pm
> To: "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxx>
> 
> Would a spoolfile be an example of a flat file on the iSeries? 

>  
> ---------------------------------

> Booth Martin

> http://www.martinvt.com

> ---------------------------------

> -------Original Message-------

>  
> From: Midrange Systems Technical Discussion

> Date: 03/07/05 15:19:22

> To: Midrange Systems Technical Discussion

> Subject: Re: E: Logical File or OPNQRYF or anyother way ?

>  
> Hi, Dave

>  
> I don't understand why you say use the term "legacy AS/400 flat-file
> architecture". I think there a misunderstanding here. A flat file, as I
> understand it, is a file which has records in which there are no fields
> (columns) defined. (And in some systems I suppose they might not even have
> the same record length.) That is what was used with early forms of RPG - and
> you COULD do it now - with I-specifications & O-specifications, where you
> define the layout of the data internally to the program. But that was not
> how it worked and works with what are called externally-defined files. Yes,
> there WAS a flat-file architecture in the System 36 - and I'm probably even
> a little wrong there. But there have been the equivalent of tables and
> indexes and all you mention since the '80s on the System 38. The 400 uses
> the same system and database architecture as the 38. The last time I
> actually USED what i think you would call a flat file in RPG was 15 years
> ago, in school, learning RPG II.

>  
> There is essentially no difference between the database on the i5 and that
> on the 38 - except for some things like triggers and referential integrity
> that were added more recently, at the time this "no-name" relational
> database got the same name as its IBM brethren. But the lack of those items
> did not make the database into flat-files.

>  
> There are charts that describe how SQL objects are implemented on the 400 -
> tables are physical files, albeit with some different attributes. Indexes
> and views are both logical files, inheriting all the general attributes
> thereof and adding the attributes that distinguish them. (This, BTW, is the
> beauty of the object-based architecture of this system.) A collection is
> nothing more than a library. Old fogies know of rows as records and columns
> as fields.

>  
> So there have ALWAYS been tables and appropriate indexes & views. We've even
> had keyed physical files all along, which are sort of like having a primary
> key, except they did not need to be unique, which disqualifies them for that
> role.

>  
> Should we use Static SQL? Maybe, although native programs called as stored
> procedures often provide better performance.

>  
> Now, I CAN create what looks like a flat file - CRTPF SOMELIB/SOMEFILE
> RCDLEN(132) will do it. But this is usually a very special case. I use that
> kind of thing for the output of a CPYSPLF command.Usually a file is created
> either using DDS or an SQL CREATE statement.

>  
> Just for fun, create a DDS source member with a variety of data types - A25,
> S5,0, say. Create the PF from it. Then use an equivalent CREATE TABLE
> (CHAR(25) NOT NULL WITH DEFAULT,DECIMAL(5,0) NOT NULL WITH DEFAULT). Then
> execute DSPFD and DSPFFD against the 2 objects - they are very close - a
> couple little differences in attributes, but both can be accessed equally
> well using SQL or native I/O.

>  
> Create a view - it is a logical file that is essentially a container for the
> SELECT statement that will be run dynamically when you access that view. And
> the view can be used in an RPG just like a good old logical file. Create an
> index with SQL and an equivalent LF with DDS - again, DSPFD will show that
> there is an access path in both, and they will look almost identical.

>  
> I guess you pushed my OK button - sorry to wax wordy - I'm sure I
> misunderstand what you mean by a flat file, so please describe what that is
> from your experience.

>  
> Thanks

> Vern
> -- 
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