Unique Key Selection

Q: My table has no primary key but the unique index is present. Can I use this table in the comparison process?
A: Yes, use unique key selection feature is described at this page.

This window allows you to select the column(s) for the records search. You can use it if the table has no Primary Key or if you want to search and compare records by another column(s). If the primary key is absent and the key is not specified, the comparison tool will not be able to perform the comparison or synchronization.

Remember that primary keys or unique keys of both tables have to contain the same number of fields.

DTM Data Comparer: Unique key selection


  • The program does not save any key definition changes into the database. It uses the unique key in the comparison project only.
  • The data sync utility shows the related toolbar button pressed if you have custom key definition: DTM Data Comparer: Key specified button
  • The software shows the toolbar button pressed with red 'P' (primary) or 'S' (secondary) sign if the unique key has been assigned automatically*: DTM Data Comparer: Key assigned button.
  • Be attentive when you select set of fields that correspond to the unique key. A non-unique key can cause data contamination during synchronization.

* - the program will try to take the primary key column from another side. It will use column or columns with same names.