Subject Unable to create unique constraint
Author André Knappstein
Hi Gang!

While preparing the final steps to migrate from dBase/FB 1.5 to C#/FB
2.5 I need to create a unique constraint for the old databases, and
need some help from someone still familiar with 1.5.

Not using uniques too often, so it's probably something I am doing
basically wrong, but I can't create the following unique constraint:

alter table T
add constraint UNQ1_T
unique (F1, F2)
using index UC_T

I receive the following error:

Invalid insert or update value(s): object columns are constrained - no 2 table rows can have duplicate column values.
attempt to store duplicate value (visible to active transactions) in unique index "@1".

I checked that at this moment the table should be "clean" from
duplicates by using the following statement:

group by
1, 2
count(T.ID) > 1

The result after the first run was a bunch of rows which would have
violated the unique. I cleared them off using a "For select..." in a
stored proc and subsequent runs yield only empty rowsets.
So the table should be ready for the unique shouldn't it?

Can somebody help me to see the forest with all these trees around,
please? What else could stop a unique like this? If I make a backup of
the database and restore it to a FB 2.5 server, the unique is created
just fine. The old server is Classic Engine, if that should matter.

Thanks in advance!

mit freundlichen Grüßen,

André Knappstein
EDV und Controlling
beta Eigenheim- und Grundstücksverwertungsgesellschaft mbH
Hafenweg 4
59192 Bergkamen-Rünthe

Telefon: +49 2389 9240 140
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