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    $options['webform_form_key'] = array('default' => NULL);

    $options['webform_join_by'] = array('default' => 'nid_cid');

    $form['webform_join_by'] = array(

      '#type' => 'select',

      '#title' => t('Relate using'),

      '#default_value' => $this->options['webform_join_by'],

      '#options' => array(

        'nid_cid' => t('Node and Component ID'),

        'cid' => t('Component ID'),

        'form_key' => t('Component Form Key'),

      ),

      '#description' => t('Choose <em>Node and Component ID</em> when this view will display data from only this webform.</br>Choose <em>Component ID</em> when this view will display data from other webforms and where the Component ID is identical.</br>Choose <em>Component Form Key</em> when this view will display data from other webforms with varying Component IDs.'),

    );

    $options =& $form_state['values']['options'];

    $options['webform_form_key'] = $options['webform_join_by_form_key'] == 'form_key' && ($node = node_load($options['webform_nid']))

                                        ? $node->webform['components'][$options['webform_cid']]['form_key']

                                        : NULL;

    // Drop PHP reference.

    unset($options);

    // When defining extra clauses, the 'table' key can be used to specify the

    // alias of another table. If NULL is specified, then the field is not

    // qualified with a table. Therefore, do NOT specify "'table' => NULL".

    switch ($this->options['webform_join_by']) {

      case 'form_key':

        $form_key = $this->options['webform_form_key'];

        $join_type = $this->options['required'] ? 'INNER' : 'LEFT';

        $this->ensure_my_table();

        $join = new views_join();

        $join->construct(

          // The table to be joined.

          'webform_component',

          // The left table (i.e. this table, webform_submission).

          $this->table,

          // The left field (i.e. the webform node id).

          'nid',

          // The field (i.e. webform_components.nid).

          'nid',

          // Extra array of additional conditions.

          array(

            array(

              // Extra join of form_key.

              'field' => 'form_key',

              // ...    = $form_key (operator '=' is default)

              'value' => $form_key,

            ),

          ),

          // Join type is the same as this relationship's join type.

          $join_type);

        $alias = $this->query->add_relationship(

          // Requested alias for new reliationship.

          'webform_component_' . $form_key,

          // Addition join to be added to this relatinship.

          $join,

          // Base table (i.e. drivingevals_submission)

          $this->table_alias,

          // Add the view to this relationship.

          $this->relationship);

        // The actual alias for this relationship's join is not known yet. Becasue

        // of name conflicts, it may have a number appended to the end. %alias is

        // substitued when the query is build with the actual alias name.

        $this->definition['extra'][] = "%alias.cid = {$alias}.cid";

        break;

      case 'nid_cid':

        $this->definition['extra'][] = array(

          'field' => "nid",

          'value' => $this->options['webform_nid'],

        );

        // FALL THROUGH.

      case 'cid':

        $this->definition['extra'][] = array(

          'field' => "cid",

          'value' => $this->options['webform_cid'],

        );

        break;

    }