Can be either a file name or a relative or absolute path name. This will be mapped in any case to an absolute relation file path on a specific host machine and server.
On success a relation file resource (cursor) is returned which must be used in any subsequent commands referencing the relation. Failure leads to a zero return value, the actual error code may be asked for by calling dbplus_errno().
This function is EXPERIMENTAL. The behaviour of this function, the name of this function, and anything else documented about this function may change without notice in a future release of PHP. Use this function at your own risk.