gives the user more options to filter the site by (like meta values)

fitlered-searchform.php

<form method="get" id="searchform" action="<?php echo home_url(); ?>/">
    <label class="hidden" for="s"><?php _e('', 'comienzo'); ?></label>
    <input type="search" class="text" value="search site" name="s" id="s" />

    <select name="sport">
        <option value="" />Choose sport</option>
        <?php
            $metakey = 'sfn_tan_choose_sport';
            $sports = $wpdb->get_col($wpdb->prepare("SELECT DISTINCT meta_value FROM $wpdb->postmeta WHERE meta_key = %s ORDER BY meta_value ASC", $metakey) );
            if ($sports) {
            foreach ($sports as $sport) {
                echo "<option value=\"" . $sport . "\">" . $sport . "</option>";
            }
        }
    ?>
    </select>

    <select name="fbposition">
        <option value="" />Choose football position</option>
        <?php
            $metakey = 'sfn_tan_football_position';
            $items = $wpdb->get_col($wpdb->prepare("SELECT DISTINCT meta_value FROM $wpdb->postmeta WHERE meta_key = %s ORDER BY meta_value ASC", $metakey) );
            if ($items) {
            foreach ($items as $item) {
                echo "<option value=\"" . $item . "\">" . $item . "</option>";
            }
        }
    ?>
    </select>

    <select name="state">
        <option value="" />Choose state</option>
        <?php
            $metakey = 'state';
            $items = $wpdb->get_col($wpdb->prepare("SELECT DISTINCT meta_value FROM $wpdb->usermeta WHERE meta_key = %s ORDER BY meta_value ASC", $metakey) );
            if ($items) {
            foreach ($items as $item) {
                echo "<option value=\"" . $item . "\">" . $item . "</option>";
            }
        }
    ?>
    </select>

    <select name="grad">
        <option value="" />Choose graduation year</option>
        <?php
            $metakey = 'sfn_tan_hs_graduation_year';
            $items = $wpdb->get_col($wpdb->prepare("SELECT DISTINCT meta_value FROM $wpdb->postmeta WHERE meta_key = %s ORDER BY meta_value ASC", $metakey) );
            if ($items) {
            foreach ($items as $item) {
                echo "<option value=\"" . $item . "\">" . $item . "</option>";
            }
        }
    ?>
    </select>

    <input type="hidden" name="post_type" value="athlete_profile" />

    <input type="submit" id="searchsubmit" value="Search" />
</form>