What should I do when having the Oracle error ORA-00936 in Subset?

Problem

I run Subset on an Oracle database using the Uniqe Append as deployment strategy.

I encounter the error ORA-00936 and don't know what to do.

ORA-00936: Missing Expression.

Solution

The most common cause is the lack of a primary key.

By using a Unique append on a table the original table is saved and the new data is joined with this data based upon an existing Primary key.

If the Primary Keys does not exist this error occurs

To fix this: 

• Create a Primary Key on the original table in the database and sync your data.
• Define a primary key in Subset. 
  To do this select the properties of the table, click your right mouse button and select Toggle Primary Key.
  This will tell Subset what the primary key which should be used in the join query.