Disable table joins for ObjectExists

[hisystems]

Currently, when the Database.ObjectExists function is called and there are table joins because:

• the key field can not be used in the WHERE clause because it will not have the alisas or prefix that is required and the SQL statement will fail.
• in most circumstances it will unnecessarily burden the database server with a table join when the key field is typically located in the main table - not in a joined table.