Re: IDDU, S36 & AS/400 SQL & RPG -Reply

Date:   12/11/97  7:56 PM
RE:     Re: IDDU, S36 & AS/400 SQL & RPG -Reply

Hi, John

Just some additions and clarifications:
<BIG Snip> -snip-
>You can CREATE TABLE into a non-SQL library. That's what I did for SQLTEST,
>as follows:
>create table pgmrvmh/sqltest (field1 char(10) not null with default)
>Lots of interesting stuff here. E.g., you can't retrieve records via an SQL
>INDEX, although it's a logical file. However, the system uses it for
>ordering records with ORDER BY clauses.
>Vernon Hamberg


Actually the INDEX (I believe) is not an Logical file.  PER SA (whatever)

The logical file is really at least 3-5 separate MI objects.  the 
file control block,  the cursor, the data space, the index(if keyed), etc.

The VIEW function of the Logical file is really, I think, in the FCB object
header. (Object specific offset I think,  Hey, This is from memory late at 
nite guys)  The index (below the MI) is a standalone object that does not 
contain the "FORMAT" of the records, in other words,  what we consider the
VIEW function of the LF - (ie. what position customer number is in).  

So it is natural that you can't read thru the INDEX object, you need the
other (Sub-MI) objects working in concert to "format" the data space 
in to "records" so to speak.  

It then follows that you CAN read thru the VIEW because that is really the 
FCB with the CURSOR with the DATA SPACE working together to  1. point to 
the correct DATA SPACE entry(cursor doing the pointing). 
The PROTO-TYPE ODP (did I mention that yet? It's the reason we can create 
a full ODP so quickly at runtime, cause it in essence does a CRTDUPOBJ of 
the PROTO-TYPE ODP stored in the FCB(I think))  then retreives the records 
back up to the higher level function (whether SQL, QUERY, OPNQRYF, or HLL)

I know we still may be confused,  but I think it's at a higher level,
and about more important things!!

Oh yea,  The logical file doesn't "OWN" the data space object. It's 
owned by the one or more physical files. The index just points to it.

I might have forgotten a couple of other MI objects, Members, etc.

(As remembered from the "The Larry Youngren & Bill Davidson show circa 1987)

Goodnight I'm Tired.
John Carr
EdgeTech

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