<input name="field_null[<?php echo $columnNumber; ?>]"
       id="field_<?php echo $columnNumber; ?>_<?php echo ($ci - $ci_offset); ?>"
       <?php if (! empty($columnMeta['Null']) && $columnMeta['Null'] != 'NO' && $columnMeta['Null'] != 'NOT NULL'): ?>
           checked="checked"
       <?php endif; ?>
       type="checkbox"
       value="NULL"
       class="allow_null"/>