Adding unique keys


It is sometimes possible to identify a table by keys other than the primary ones. These are (combinations of) columns that have key characteristics (unique and non null); they are called unique keys.

Unique keys are preceded by a sequential number enclosed in brackets: <1> for the first unique key, <2> for the second, etc.

To create an alternate key:
  1. Look for the Key tool and click the arrow next to the key (a display of keys numbered 1 to 5 will appear).
  2. Choose one of those numbered keys.
  3. Click the column(s) that will become the unique key.