php - switch case 在查询中被忽略

Question

我有一个在 switch case 中设置的查询。 while 循环遍历我的行，并打印出 3 个随机行，其中 id, weekday, description 列中的数据被打印出来。

while 循环正在运行并打印出 3 个随机行。但似乎开关盒完全被忽略了。无论我在选择表单中选择星期三还是星期六，我都会得到星期三和星期六的混合打印。

表格的目的是让我可以分类为仅分别查看星期三和星期六。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

如果已设置，您将开启，而不是实际值。检查它是否已设置，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;
  }
}