[Info-vax] Help with DECBasic: reading a record in an INDEX SEQ file using a compound key

[Randy Park]

thick_guy_9 wrote:
> All
> I need some help with DECBasic. All the examples in the BASIC USER
> GUIDE use a simple key.
> 
> This is how I open the file:
> 
> OPEN sFILENAME  AS FILE #1  &
> ,access         modify      &
> ,allow          modify      &
> ,map            REC_MAP		&
> ,organization   indexed     &
> ,primary        (PAN, DOB)  ! <======= NOTE &
> ,alternate      LAST  duplicates changes &
> ,alternate      FIRST duplicates changes
> 
> FIND #1, KEY #0 EQ "sMyPAN,sDOB", REGARDLESS
> GET #1
> The above Get command gives me a "RECORD NOT FOUND" error.
> 
> Did I get the syntax correctly?
> 
> Thanks!

It's been 10 years since I used Dec BASIC, but I did use it for over 15 years 
and was pretty good at it.  So here goes.

1.  The "primary" and "alternate" clauses are useful only if creating the file. 
  You don't need them for opening an existing file.

2.  PAN and DOB should be fixed length strings found in the map REC_MAP

3.  If sMyPAN and sDOB are dynamic strings of the exact same length as PAN and 
DOB then you can use the following:
	sTEMP = sMyPAN + sDOB
	GET #1, KEY #0 EQ sTEMP, REGARDLESS
For possible future debugging, I prefer using a temporary string (sTEMP).

4.  If sMyPAN and sDOB are not the exact same length as PAN and DOB then do the 
following:
	PAN = sMyPAN		!force correct length
	DOB = sDOB		!force correct length
	sTEMP = PAN + DOB
	GET #1, KEY #0 EQ sTEMP, REGARDLESS

5.  In designing your indexed file I recommend against have last_name by itself 
as an index.  Same with first_name.  You'll end up with way too many duplicates. 
  I recommend a multi segmented alternate key comprised of last_name and 
first_name, and another multi segmented alternate key comprised of first_name 
and last_name.

6.  Performing a FIND statement followed by a GET statement, is really a waste 
of time.  Just perform the GET statement.

7.  Hopefully you are not using BASIC to create your indexed file.  The RMS 
utilities do a better job and offer more functionality and flexibility.  I want 
to say the utility is EDIT/FDL and CREATE/FDL but I could be wrong.

8.  Finally, you understand the implications of REGARDLESS don't you?  You are 
bypassing the record locking protections by using it.

Good luck.