Non-Unique Index

You can define a non-unique index on any Column or set of Columns.

Unlike a Primary or Unique Key, a non-unique index does not validate each row for a unique value but allows different rows to have the same value in the Column or set of Columns that are part of the index.

Like other indexes, a non-unique index keeps rows sorted on the specified Column or Columns so that the system can use faster search algorithms on the table, speeding up queries on the table.

To define a non-unique index, do the following:

1. Select Non-Unique Index from the Type drop-down list. The system refreshes the lower portion of the screen and lists all the Columns you have defined in the current Table instance in the Table Columns side of the shuttle.
2. Select the Column or Columns you want to be part of the unique key and move them into the Non-Unique Index side of the shuttle. You can use Shift+Click or Ctrl+Click to select the Columns. You can double-click to move them or use the arrows.
3. If necessary, use the Up and Down arrows to reorder the Columns in the key. You should have the most general Column at the top and the most granular at the bottom. For example, if your non-unique key is Patient, Visit, Test, you should list them in that order.
4. Click Apply.