如何在動態下拉菜單中設置默認值

Question

我有一個從MySQL database動態填充的drop down select ，我需要默認下拉值以根據用戶選擇的記錄顯示。 到目前為止，我沒有在下拉列表中顯示任何值。 但是我的代碼在select選項語句之外，並且以粗體顯示默認值。 我似乎無法理解if語句邏輯。

用戶從數據表中選擇一條記錄，然后單擊“編輯”。 例如，用戶選擇了以灰色突出顯示的行，然后單擊“ edit”（將其發送到編輯表單）

編輯表單：我將單位ID傳遞給編輯表單，並根據傳遞的ID預填充輸入字段，但是在這里我無法填充並設置默認的下拉選項值

這是下拉選擇（div id下拉）的編輯表單后面的代碼

    define('DBHOST','localhost');
    define('DBUSER','root');
    define('DBPASS','*********');
    define('DBNAME','fdmamaint');

    if (!$db = new mysqli(DBHOST, DBUSER, DBPASS, DBNAME)) die("Can't connect to database");

 // Retrieve the record the user selected
    $id = htmlspecialchars($_GET["id"]); 

// Query the depunits table based on the user selection 
    $sql = "SELECT unit_id, div_id, title_org, short_desc, long_desc, unit_desc, avail_ind "
            . "FROM depunits "
            . "WHERE unit_id=$id";
    if (!$result = $db->query($sql)){
            die("There was an error running the query [" .$db->error. "]");
    }

// Walk through the result set and assign variables for reference later on in the script
    while ($row = $result->fetch_assoc()){
        $unitId = $row['unit_id'];
        $divId = $row['div_id'];
        $titleOrg = $row['title_org'];
        $shortDesc = $row['short_desc'];
        $unitDesc = $row['unit_desc'];
        $longDesc = $row['long_desc'];
        $enabled = $row['avail_ind'];
    }

  // Div Id - query database to get drop down select options
    $divSelect = "SELECT div_id, long_desc FROM depdivisions "
            . " WHERE div_id <> '' and avail_ind='Y' and active_ind='Y'"
            . " ORDER BY div_id";
    if (!$divResult = $db->query($divSelect)){
            die("There was an error running the query [" .$db->error. "]");
    }

.......

動態下拉選擇：

<!-- Div Id -->                                        
<label for="divId" class="control-label">Div Id</label>
   <select class="form-control" name="divId" id="divId">
       <option value=" "></option>
       <?php
          while ($rowDivs = $divResult->fetch_assoc()) 
         {
            $data = '37' .$rowDivs['div_id'];

            // if the value of $data matches the value of div id of the 
            // user selected row in the database then give that option 
            // value the selected tag                                      
            if ( $data == $divId) 
            {
               echo "<option value=". $data ."selected>";
               echo $data ;
               echo "</option>";
            }
            else 
            {
               echo "<option value=". $data .">";
               echo $data;
               echo "</option>";
            }
          }

我可以在while語句中有if / else語句嗎？ 這也許就是為什么我沒有在下拉菜單中得到任何數據結果的原因嗎？

Answer 1

我想到了：

我需要使用內聯if語句，如下所示：

<!-- Div Id -->                                        
<label for="divId" class="control-label">Div Id</label>
   <select class="form-control" name="divId" id="divId">
       <option value=" "></option>
       <?php
          while ($rowDivs = $divResult->fetch_assoc()) {

              $data = '37' .$rowDivs['div_id'];
              echo "<option value=$data" .($data == $divId ? ' selected="selected"' : '') . ">$data</option>";  
          }     
       ?>
   </select>