<select class="js-example-templating" name="mem1">
            <?php
              $query = "select * from user";
              $query_result = query($query);
            while($row = fetch_array($query_result)) {
                echo "<option value='{$row['user_id']}'>{$row['user_id']} - {$row['name']}</option>";
            }
            ?>
          </select>
          <br><br>
          <select class="js-example-templating" name="mem2">
            <?php
              $query = "select * from user";
              $query_result = query($query);
            while($row = fetch_array($query_result)) {
                echo "<option value='{$row['user_id']}'>{$row['user_id']} - {$row['name']}</option>";
            }
            ?>
          </select>
          <br><br>
          <select class="js-example-templating" name="mem3">
            <?php
              $query = "select * from user";
              $query_result = query($query);
            while($row = fetch_array($query_result)) {
                echo "<option value='{$row['user_id']}'>{$row['user_id']} - {$row['name']}</option>";
            }
            ?>
          </select>

function formatState (state) {
  if (!state.id) {
    return state.text;
  }
    var $state = $(
    '<span>' + state.text + '</span>'
  );
  return $state;
};
$(".js-example-templating").select2({
  templateResult: formatState
});
</script>