Reads in any unread LOB data. For long char fields, we may already have up to odbc_longreadlen() bytes in the buffer. These are passed in via the $curdata parm. For long binary fields, no data is read initially since odbc_binmode() is set to ODBC_BINMODE_PASSTHRU.
If the current ODBC driver does not support LIMIT or OFFSET natively, the methods in here perform some adjustments and extra checking to make sure that this behaves the same as RDBMS drivers using native OFFSET/LIMIT.
NOTE: If the driver you are using does not support the odbc_num_rows() function, then you should use the ODBCCachedResultSet class instead.