Assume you have a table like this:
Fld1 Fld2 Fld3 Fld4
1 1 1 1
1 1 1 2
1 2 1 3
1 1 1 4
1 1 1 1
Fld1, Fld2, Fld4, Fld4 are your composite key fields. That is, the fields for your key.
Note Record 1 and record 5 are the same.
The query to find duplicated values in, let say, Fld4 is:
T1.DB | Fld1 | Fld2 | Fld3 | Fld4 |
| Check | Check | Check | Check calc count all |
Your results:
Fld1 Fld2 Fld3 Fld4 Count of Fld4
1 1 1 1 2.00
1 1 1 2 1.00
1 1 1 4 1.00
1 2 1 3 1.00
In Count of Fld4 column, value > 1 are records with duplicated values in Fld4.
Now, if you are running into key violation problem. I believe you have a design problem and should consider using different fields for your key.