Abstract class to read rows from a query result
Close the reader discarding any unread results.
Yield each row to the given block as a Hash
Return the number of fields in the result set.
Return the array of field names
Discard the current row (if any) and read the next one (returning true), or return nil if there is no further row.
Return the array of field values for the current row. Not legal after next! has returned false or before it‘s been called
[Validate]