Host variable <str> is ambiguous in the host file Explanation: The ANSI and ISO SQL standards require that host variable names be unique in the entire file being preprocessed. The SQL interface to Oracle Rdb only requires it to be unique in its language scope. This host variable is not unique in the file. User Action: If it is important to have only standard features in your program, you should change the name of this host variable to make it unique in the file.