Old code snippet for creating forms manually using the form API in Drupal.

NewFormDrupal.php

<?php

/**
 * Implementation of hook_elements().
 */
function referralsources_elements() {
  return array('referralsources_select' => array(
    '#input' => TRUE,
    '#process' => array('referralsources_select_process'),
    '#element_validate' => array('referralsources_select_validate'),
  ));
}

/**
 * Implementation of form_type_hook_value().
 */
function form_type_referralsources_select_value($element, $edit = FALSE) {
  if (func_num_args() == 1) {
    if (empty($element['#default_value']['referralsources_rid'])
      && !empty($element['#default_value']['referralsources_other'])) {
      // If no rid is empty and other is not, make 'Other' the default selection (instead of "Please select...")
      $element['#default_value']['referralsources_rid'] = t('OTHER');
    }
    return $element['#default_value'];
  }
}

/**
 * Template form for selecting referral source.
 * Can be embedded anywhere and referral source data will be recorded in DB.
 *
 * @param[in,out] $form_state
 *   Standard FAPI $form_state variable.
 * @param[in] $rsid
 *   ID of FAPI referral sources record to load (optional)
 * @param[in] $submit_button
 *   If TRUE, this function will add a Submit button to the form.
 * @param[in] $fieldset
 *   If TRUE, the referral source selection items will be wrapped in a fieldset.
 * @param[in] $weight
 *
 */
function referralsources_select_form(&$form_state, $rsid = NULL, $submit_button = FALSE, $fieldset = TRUE, $weight = 0, $rstid = REFERRALSOURCE_SUBMISSION_TYPE_FAPI) {
  global $user;

  if (!empty($rsid)) {
    // Load specified referral source selection record
    $data = db_fetch_array(db_query("SELECT form_id, uid, rid, other FROM {referralsources_submissions} WHERE rsid = %d", $rsid));
  }

  // Define form items
  $item_referralsources_rsid = array(
    '#type' => 'value',
    '#value' => check_plain($rsid),
  );
  $item_referralsources_rstid = array(
    '#type' => 'value',
    '#value' => check_plain($rstid),
  );
  $item_referralsources_uid = array(
    '#type' => 'value',
    '#value' => $user->uid,
  );
  $item_referralsources_select = array(
    '#type' => 'referralsources_select',
    '#default_value' => array(
      'referralsources_rid' => isset($data['rid']) ? check_plain($data['rid']) : NULL,
      'referralsources_other' => isset($data['other']) ? check_plain($data['other']) : '',
    ),
  );

  // Build form
  $form = array();
  if ($fieldset) {
    // Wrap referralsource selection in fieldset
    $form['referralsource'] = array(
      '#type' => 'fieldset',
      '#title' => check_plain(variable_get('referralsource_fieldset_title', REFERRALSOURCE_FIELDSET_TITLE_DEFAULT)),
      '#description' => check_plain(variable_get('referralsource_fieldset_description', REFERRALSOURCE_FIELDSET_DESCRIPTION_DEFAULT)),
      '#collapsible' => TRUE,
      '#collapsed' => FALSE,
    );
    $form['referralsource']['referralsources_rsid'] = $item_referralsources_rsid;
    $form['referralsource']['referralsources_rstid'] = $item_referralsources_rstid;
    $form['referralsource']['referralsources_uid'] = $item_referralsources_uid;
    $form['referralsource']['referralsources_select'] = $item_referralsources_select;
    $form['referralsource']['#weight'] = $weight;
  }
  else {
    // Display referralsource selection without fieldset
    $form['referralsources_rsid'] = $item_referralsources_rsid;
    $form['referralsources_rstid'] = $item_referralsources_rstid;
    $form['referralsources_uid'] = $item_referralsources_uid;
    $form['referralsources_select'] = $item_referralsources_select;
    $form['referralsources_select']['#weight'] = $weight;
  }
  if ($submit_button) {
    // Add submit button to form.
    $form['submit'] = array(
      '#type' => 'submit',
      '#value' => t('Submit'),
      '#weight' => 999,
    );
  }

  // Explicitly specify submit callback in case this is being embedded in another form
  $form['#submit'][] = 'referralsources_select_form_submit';

  return $form;
}

/**
 * Submit callback for referral source template FAPI form.
 */
function referralsources_select_form_submit($form, &$form_state) {
  if (!empty($form_state['values']['referralsources_select']['referralsources_rid'])
    || !empty($form_state['values']['referralsources_select']['referralsources_other'])) {
    // Save referral source selection to DB
    db_query("UPDATE {referralsources_submissions} SET rstid = '%s', form_id = '%s', uid = %d, rid = %d, other = '%s', created_datetime = '%s' WHERE rsid = %d",
      $form_state['values']['referralsources_rstid'] , $form_state['values']['form_id'], $form_state['values']['referralsources_uid'],
      $form_state['values']['referralsources_select']['referralsources_rid'],
      $form_state['values']['referralsources_select']['referralsources_other'], date('c'), $form_state['values']['referralsources_rsid']
    );
    if (db_affected_rows() == 0) {
      db_query("INSERT INTO {referralsources_submissions} (rstid, form_id, uid, rid, other, created_datetime) VALUES ('%s', '%s', %d, %d, '%s', '%s')",
        $form_state['values']['referralsources_rstid'], $form_state['values']['form_id'], $form_state['values']['referralsources_uid'],
        $form_state['values']['referralsources_select']['referralsources_rid'],
        $form_state['values']['referralsources_select']['referralsources_other'], date('c')
      );
      // New referral source selection record added to DB, add id value to form for submit handlers to use
      $form_state['values']['referralsources_rsid'] = db_last_insert_id("{referralsources_submissions}", 'rsid');
    }
  }
}

/**
 * Process callback for referral source select element
 */
function referralsources_select_process($element, $edit, &$form_state, $complete_form) {
  // Build the element
  $element['#tree'] = TRUE;
  $element['referralsources_rid'] = array(
    '#type' => 'select',
    '#title' => check_plain(variable_get('referralsource_select_label', REFERRALSOURCE_SELECT_LABEL_DEFAULT)),
    '#options' => referralsources_select_options(),
    '#default_value' => check_plain($element['#value']['referralsources_rid']),
  );
  $element['referralsources_other'] = array(
    '#type' => 'textfield',
    '#title' => check_plain(variable_get('referralsource_other_label', REFERRALSOURCE_OTHER_LABEL_DEFAULT)),
    '#size' => 50,
    '#maxlength' => 255,
    '#default_value' => check_plain($element['#value']['referralsources_other']),
  );
  return $element;
}

/**
 * Returns array of referral source options for select lists
 */
function referralsources_select_options($flat = FALSE) {
  static $options = array();
  static $options_flat = array();

  if (empty($options)) {
    // Get referral sources from DB
    $result = db_query("SELECT rid, title, grouping FROM {referralsources} ORDER BY weight asc");
    while ($row = db_fetch_object($result)) {
      if (variable_get('referralsource_group_select_list', TRUE)) {
        // Create a grouped list of referral sources
        if (!empty($row->grouping)) {
          $options[$row->grouping][$row->rid] = $row->title;
        }
        else {
          $options['Other'][$row->rid] = $row->title;
        }
      }
      else {
        // Create a flat list of referral sources
        $options[$row->rid] = $row->title;
      }
    }
  }

  if ($flat) {
    // Remove grouping from options, reduce to key/value pairs (return array of valid options).
    if (empty($options_flat)) {
      foreach ($options as $k => $v) {
        if (is_array($v)) {
          foreach ($v as $k => $v) {
            $options_flat[$k] = $v;
          }
        }
        else {
          $options_flat[$k] = $v;
        }
      }
    }
    $return = $options_flat;
  }
  else {
    // Return grouped array of options for select list.
    $return = $options;
    // Add "Please select one..." option to beginning of select list.
    $return = array_merge(array('' => array('' => t('Please select one...'))), $return);
    // Add "Other" option to end of select list.
    $return['Other']['OTHER'] = t('Other (please specify below)');
  }

  return $return;
}

/**
 * Theme function for displaying referral source select element
 */
function theme_referralsources_select($element) {
  $output = $element['#children'];
  return $output;
}