在查询中忽略switch case

Question

我有一个查询，我在switch case中设置。 while循环遍历我的行，并打印出3个randoms行，其中列id, weekday, description中的数据被打印出来。

while循环正在工作并打印出3个随机行。但似乎开关案件完全被忽视。无论选择星期三还是星期六，我都会在星期三和星期六获得混合打印。

该表格的目的，是我可以排序只能看到星期三和星期六单独。有人知道为什么会这样吗？

HTML

<select name="weekday" class="form-control selectpicker" > 
      <option value=" ">Select Weekday</option> 
      <option value="alldays">All Days</option> 
      <option value="wednesday">Wednesday</option> 
      <option value="saturday">Saturday</option> 
    </select> 
    <form method="post"> 
     <button class="btn btn-warning">Shuffle</button> 
    </form> 

PHP

<?php 
    $sql = "SELECT id, weekday, description FROM articles"; 
     switch(isset($_POST['weekday'])){ 
     case 'wednesday': 
      $sql .= " WHERE weekday LIKE 'Wednesday'"; 
     break; 
     case 'saturday': 
      $sql .= " WHERE weekday LIKE 'Saturday'"; 
     break; 
     } 
     $sql .= " ORDER BY RAND () LIMIT 3"; 

     $res = $mysqli->query($sql); 


    if ($res->num_rows > 0) { 
     while($row = $res->fetch_assoc()) { 
      echo "article Number: " . $row["id"]. "<br>" . 
       "Weekday: " . $row["weekday"]. "<br>" . 
       "Description: " . $row["description"]. "<br><br>". 
       '<div class="btn btn-warning btn-open-modal" data-id="'.$row["id"].'">See Details '.'</div><br><br>';    
     } 
    } else { 
    echo "0 results"; 
    } 
?> 

Answer 1

，如果它的设置，而不是实际值你接通。检查它是否设置，然后进入开关选项：

if(isset($_POST['weekday'])) { 
    switch($_POST['weekday']){ 
    case 'wednesday': 
     $sql .= " WHERE weekday LIKE 'Wednesday'"; 
    break; 
    case 'saturday': 
     $sql .= " WHERE weekday LIKE 'Saturday'"; 
    break; 
    } 
}