GPV in report designer, data model

I had a tricky bug I just spent hours on, and was wondering if anyone could
explain it, or if they've run into it. I'm using Pdox 9 sp3.

An existing report had a data model of:
Child table - primary key: RecID, Date1, Time1, Seq1
Master table - primary key: RecID; (with fields Company1 & Emp1)
Company table - primary key: Company1
Employee table - primary key: Emp1

My data model used the Child table as the main table, with a 1-1 link to
Master. Master had a 1-1 link to both Company & Employee. This has worked
fine for the year or so since the report was created.

I wanted to add a new table, that looked a lot like the Child table:
Child2 table - primary key: RecID, Date1, Time1, Seq1

I tried to add this to the data model, with Child having a 1-1 link to Child2
(by including all 4 key fields). When I ran the report, without even adding
any of the fields from Child2, I got a GPV immediately.

If I dropped Seq1 from the link, it ran fine.

After much experimenting, I removed Child2 from my data model. Then I unlinked
Child from Master. I added back Child2 & relinked it with all 4 fields.
Then, I relinked Child to Master. This seems to have fixed it.

Can anyone explain why the sequence of how the tables are linked matters?
Is it because of the length of the linked keys? Is there a rule to be followed?


Thanks,
Jim Moseley

ps. To further confuse me, I got a GPV when I tried to unlink Master from
Child, while Child2 was still linked. I had to unlink Child2 first, then
Master, then add back Child2, then add back Master. Very strange.

Jim

can you recreate the GPV by creating your original report and then adding
the new table?

--
Bertil Isberg - CTECH
Paradox buglist:
online: http://hem.bredband.net/bertilisberg/

"Jim Moseley" skrev i meddelandet

>
> I had a tricky bug I just spent hours on, and was wondering if anyone
> could
> explain it, or if they've run into it. I'm using Pdox 9 sp3.
>
> An existing report had a data model of:
> Child table - primary key: RecID, Date1, Time1, Seq1
> Master table - primary key: RecID; (with fields Company1 & Emp1)
> Company table - primary key: Company1
> Employee table - primary key: Emp1
>
> My data model used the Child table as the main table, with a 1-1 link to
> Master. Master had a 1-1 link to both Company & Employee. This has
> worked
> fine for the year or so since the report was created.
>
> I wanted to add a new table, that looked a lot like the Child table:
> Child2 table - primary key: RecID, Date1, Time1, Seq1
>
> I tried to add this to the data model, with Child having a 1-1 link to
> Child2
> (by including all 4 key fields). When I ran the report, without even
> adding
> any of the fields from Child2, I got a GPV immediately.
>
> If I dropped Seq1 from the link, it ran fine.
>
> After much experimenting, I removed Child2 from my data model. Then I
> unlinked
> Child from Master. I added back Child2 & relinked it with all 4 fields.
> Then, I relinked Child to Master. This seems to have fixed it.
>
> Can anyone explain why the sequence of how the tables are linked matters?
> Is it because of the length of the linked keys? Is there a rule to be
> followed?
>
>
> Thanks,
> Jim Moseley
>
> ps. To further confuse me, I got a GPV when I tried to unlink Master from
> Child, while Child2 was still linked. I had to unlink Child2 first, then
> Master, then add back Child2, then add back Master. Very strange.