SQL Server Partitioning - Unique Index Error

Or you create NON-partitioned index, or you HAVE to include the partitioning key into partitioned index like this:

Partitioned index

CREATE UNIQUE NONCLUSTERED INDEX [IX_ID_ON_PS_DATETIME] ON [CRD].[TRANSACTION] 
(
    [ID] ASC,
    TRANSACTION_DATE_TIME
) ON [PS_DATETIME_WEEKLY]([TRANSACTION_DATE_TIME])

OR

Non-partitioned index

CREATE UNIQUE NONCLUSTERED INDEX [IX_ID_ON_PS_DATETIME] ON [CRD].[TRANSACTION] 
(
    [ID] ASC
) ON PRIMARY

From the TechNet Microsoft page

When partitioning a unique index (clustered or nonclustered), the partitioning column must be chosen from among those used in the unique index key. If it is not possible for the partitioning column to be included in the unique key, you must use a DML trigger instead to enforce uniqueness.

So to implement a workaround you can check this link out... one workaround from the blog and another one in the comments

Dealing with Unique Columns when Using Table Partitioning