When the Target Database is Oracle and I try to create a Function Based Index, why can I create it for IE (non-unique) Indexes, but not for AK (unique) Indexes?

Question:

When the Target Database is Oracle and I try to create a Function Based Index, why can I create it for IE (non-unique) Indexes, but not for AK (unique) Indexes?

Answer:

This functionality is by design since Oracle only supports Function Based Indexes and does not support Function Based Constraints.  To create Function Based Indexes for a Unique Index (AK) you can perform the following:

1. Create a Table and right-click > Select Index Properties...

2. Create a Unique Index (AK)                                                 

3. Deselect the checkbox 'Generate As Constraint' for the index                     

4.  In the Members tab, under the Index Members section click the empty field next to "1" to activate the "New" Button where an expression can be filled in   

5. Click the OK button to save the contents in the Expression window