在下拉，等於給mysql的輸出

Question

我有一個多dropdownbox這就是從像阿姆斯特丹，鹿特丹，邁阿密，紐約msyqli輸出產生的值選擇值......

我想選擇值什麼等於$貓的值

到目前爲止它沒關係。

但問題是下拉列表有重複的值。 Click here to show the problem 我該如何解決這個問題？

$resultxx = mysqli_query($database->connection,"SELECT city FROM postcode 
GROUP BY city") or die(mysqli_error()); 


    $cats = explode(",", $ed['ophaal_locaties']); 

    while($land = mysqli_fetch_array($resultxx)){ 
    $city = $land['city']; 

    foreach($cats as $cat) { 
    $cat = trim($cat); 

    if($cat == $city){ 
    $sl = 'selected'; 
    }else{ 
    $sl = ''; 
    } 

     echo "<option ".$sl.">".$city."</option>"; 
    } 
} 

Answer 1

嘗試使用下面的SQL查詢 -

SELECT DISTINCT(city) FROM postcode