public byte[] getBytes(String columnName) throws SQLException {
      return getBytes(getColIdxByName(columnName));
   }
Retrieves the value stored in the designated column
of the current row as a <code>byte</code> array.
The bytes represent the raw values returned by the driver.

@param columnName a <code>String</code> object giving the SQL name of
       a column in this <code>StreamingRowSetImpl</code> object
@return the column value as a <code>byte</code> array in the Java programming
language; if the value is SQL <code>NULL</code>, the result is <code>null</code>
@throws SQLException if (1) the given column name is not the name of
a column in this rowset, (2) the cursor is not on one of
this rowset's rows or its insert row, or (3) the designated
column does not store an SQL <code><b>BINARY</b>, <b>VARBINARY</b>
</code> or <code>LONGVARBINARY</code> values
The bold SQL type designates the recommended return type.
@see #getBytes(int)
src/main/java/org/replicadb/rowset/StreamingRowSetImpl.java