The following are the flags that you may want to use at database open time. Note that this list is not exhaustive — it includes only those flags likely to be of interest for introductory, single-threaded database applications. For a complete list of the flags available to you, see the Berkeley DB C++ API Reference Guide.
		To specify more than one flag on the call to 
		
        Db::open(),
		you must bitwise inclusively OR them together:
	
u_int32_t open_flags = DB_CREATE | DB_EXCL;
				DB_CREATE
			
If the database does not currently exist, create it. By default, the database open fails if the database does not already exist.
				DB_EXCL
			
				Exclusive database creation. Causes the database open to fail if the database 
				already exists.  This flag is only meaningful when used with 
				DB_CREATE.
			
				DB_RDONLY
			
Open the database for read operations only. Causes any subsequent database write operations to fail.
				DB_TRUNCATE
			
Physically truncate (empty) the on-disk file that contains the database. Causes DB to delete all databases physically contained in that file.