ORIGINAL_DB_NAME (Transact-SQL)
Returns the database name that is specified by the user in the database connection string. This is the database that is specified by using the sqlcmd-d option (USE database) or the ODBC data source expression (initial catalog =databasename).
This database is not the same as the default user database.
Syntax
ORIGINAL_DB_NAME ()
Remarks
If the initial database is not specified, the function returns an empty string.