When Fully Qualified Names Are Required
Using unqualified names is easiest when the default database is the only database referred to by an SQL statement. When an SQL statement references tables, views, or other objects from more than one database, unqualified names can apply to only one of those databases.
When encountering an unqualified table name, the system looks for an object by that name in all of the following databases:
The search must find the table name in only one of those databases. Teradata Database returns the “ambiguous table name” error message if the table name exists in more than one of those databases. The default database does not receive priority over any other database.
Therefore, if you reference more than one database, you must use the fully qualified form for names that are contained in more than one of the databases.
The following syntax shows the fully-qualified form referencing, for example, a table: