forech 显示比数据库少一行答案

【问题标题】：forech shows one row less than the databaseforech 显示比数据库少一行
【发布时间】：2021-10-01 04:06:35
【问题描述】：

我有一个 if 语句，如果我的表中存在某种条件，它会动态显示 html，其中包含数据库中存在的每一行的数据，我正在使用 foreach 循环，但它一直显示在较少的行上比实际表中的内容，如果它有三行，它将显示两行，如果只有一个它不显示任何内容，它会通过 if 语句，因为如果它不显示错误消息，但在我的如果它只是显示一个空白页面，为什么会发生这种情况？

function show()
{
   
    $stmt = $this->db->prepare("SELECT offered_rides.*, reg.*
                                FROM offered_rides
                                 JOIN reg ON offered_rides.phone = reg.phone where 
                                 offered_rides.date = :date AND offered_rides.seats >= :seats AND offered_rides.start = :start AND offered_rides.finish = :finish ");
    $stmt->bindParam(':date',$this->date);
    $stmt->bindParam(':seats',$this->seats);
    $stmt->bindParam(':start',$this->from);
    $stmt->bindParam(':finish',$this->to);
    $stmt->execute();
    $row = $stmt->fetch(PDO::FETCH_ASSOC);
    
    
    
   if($row)   
   { 
           
      foreach($stmt as $row):
            
          
         ?>

        <form action="Update.php" method="POST">
            
            <div class="a">
                
                <div class="fnamelname">
                <p style="display:inline;"> <?php echo $row["fname"];?>  </p>
                <p style="display:inline;"> <?php echo $row["lname"];?> </p>
                </div>
                    
            </div>
                
            
            //i need to store these to use them later
            <input type = "hidden" name = "phone-D" value = "<?=$row['phone'] ?>" />
            <input type = "hidden" name = "time" value = "<?= $row['time'] ?>" />
            <input type = "hidden" name = "seats" value = "<?= $row['seats'] - $this->seats?>" />
             
            
        </form>

        <?php endforeach; 
        
        
   }

【问题讨论】：

标签： php html pdo

【解决方案1】：

这完全没有意义：foreach($stmt as $row):。 $stmt 不是数组，它是单个对象。相反，您应该使用带有$row = $stmt->fetch(PDO::FETCH_ASSOC); 步骤的while 循环作为条件。因为fetch() 方法每次调用都会返回一行。这就是你想要的。

function show() {
   
    $stmt = $this->db->prepare("SELECT offered_rides.*, reg.* FROM offered_rides JOIN reg ON offered_rides.phone = reg.phone WHERE  offered_rides.date = :date AND offered_rides.seats >= :seats AND offered_rides.start = :start AND offered_rides.finish = :finish ");
    $stmt->bindParam(':date',$this->date);
    $stmt->bindParam(':seats',$this->seats);
    $stmt->bindParam(':start',$this->from);
    $stmt->bindParam(':finish',$this->to);
    $stmt->execute();


    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        ?>

        <form action="Update.php" method="POST">                
            <div class="a">
                <div class="fnamelname">
                <p style="display:inline;"> <?php echo $row["fname"];?>  </p>
                <p style="display:inline;"> <?php echo $row["lname"];?> </p>
                </div>
            </div>
            //i need to store these to use them later
            <input type = "hidden" name = "phone-D" value = "<?=$row['phone'] ?>" />
            <input type = "hidden" name = "time" value = "<?= $row['time'] ?>" />
            <input type = "hidden" name = "seats" value = "<?= $row['seats'] - $this->seats?>" />
        </form>

        <?
    }
}

还有一个提示：当你在 php 中使用“短标签”时，你的 html 标记会更容易阅读：

        <form action="Update.php" method="POST">                
            <div class="a">
                <div class="fnamelname">
                <p style="display:inline;"><?= $row["fname"]?></p>
                <p style="display:inline;"><?= $row["lname"]?></p>
                </div>
            </div>
            //i need to store these to use them later
            <input type="hidden" name="phone-D" value="<?=$row['phone']?>"/>
            <input type="hidden" name="time" value="<?= $row['time']?>"/>
            <input type="hidden" name="seats" value="<?= $row['seats'] - $this->seats?>"/>
        </form>

【讨论】：