[U2] - Can a program determine File doesn't exist in TRANS()

[George Gallen]

This is UV11 I'm currently running on

if you have  X=TRANS("SOMEFILE","ID",1,'X')

I haven't found any way to programmatically determine that SOMEFILE doesn't exist from the TRANS() read

aside from executing a TRANS("VOC","SOMEFILE",-1,'X") first to see if it's in the VOC at all - if I go that route

might as well switch to an OPEN/READ

I've tried V and C vs ('X') - X and V trigger a runtime warning - but if it's running as a phantom

that doesn't help.  C will return the ID if it doesn't exist - or if the combo of file/id doesn't exist

I can always swap to an OPEN / READ and have the OPEN trigger the file doesn't exist

but trying to reduce my OPENs for TRANS() for those 1x read only requests and use

OPEN only with WRITEs or if I need to lock a record on READ.

Any other ideas other than preface with a VOC read?

[KOSDAY SOLUTIONS]

Play with STATUS function after TRANS

In my tests STATUS() returns a "2" when the file or record does not exist. If the TRANS is correct STATUS() returns a "0".

Angel

[George Gallen]

Thanks.

At first I didn't think there would be much difference between using 'C' vs 'X' which would

return the ID if the file or ID was not found from TRANS() and status()

but with playing the STATUS() return 0 if good read OR good file/no record id - and only 2 if the file

is not found.  and using 'C' vs 'X' returns the ID instead of "" if the record is not found.

so - if status() = 0 and data returned # ID - good file / good record

        if status() = 0 and data returned = ID - good file / recordid does not exist

        if status() = 2 bad file

using 'C' instead of 'X' or 'V' will eliminate the run time error being displayed

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From: mvd...@googlegroups.com <mvd...@googlegroups.com> on behalf of KOSDAY SOLUTIONS <kosdays...@gmail.com>
Sent: Thursday, March 24, 2022 12:03 PM
To: Pick and MultiValue Databases <mvd...@googlegroups.com>
Subject: [mvdbms] Re: [U2] - Can a program determine File doesn't exist in TRANS()

 

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