How to create a combined index?

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1 total messages Started by Lothar Brandner Thu, 26 Apr 2007 12:33

#167

Author: Lothar Brandner
Date: Thu, 26 Apr 2007 12:33

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Hello,
I am trying to set up a combined index for an m:n connection between two 
tables. There exists an MS-Access table C which holds the lookup values from 
table A and B. Every possible combination may only exist once.So I defined 
the index for Table C as a unique combination  of both the values from table 
A and B. This works fine: MS Access does not acceppt double 
indices(combinations of values from table A and B).
In my C++-Application (BDS 2006 Enterprise) I use three TADOTables for Table 
A, B and C.
In TAdoTable C I defined two additional data elements as foreign keys for 
table A and B.
Now I can select all possible values each for table A and B, but I could not 
find a way how to avoid double combinations.
If the application's user accidentally generate a combination which already 
exists in the database the application throws an exception (this is correct, 
I told MS access not to accept double indices).
Is there a simple way to tell ADOTable C not to accept multiple indices?
Greetings
Lothar

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