Question

每次访问我的索引页面时，我都需要检查数据库中是否已存在记录，如果存在，则需要更新字段'count'，否则会添加一行。

我设法让它在访问时创建一行，但如果行已经存在，似乎无法更新计数。

// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);
// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

// Check to see if record exists
$sql = "SELECT * FROM page_tracking where name ="index.php"";
if (mysqli_query ($conn, $sql)) {
	$sql= "UPDATE page_tracking SET count=count+1 where name= "index.php")";
}

else if {
//Insert Query
$sql = "INSERT INTO page_tracking (name, count)
VALUES ('index.php', '1')"; 
}
if (mysqli_query($conn, $sql)) {
    echo "Thanks for visiting! Your visit has been recorded";
} else {
    echo "Unfortunately we were unable to record your visit: " . $sql . "<br>" . mysqli_error($conn);
}

可能有一个非常简单的解释！问题肯定是'检查记录是否存在'的代码

Answer 1

在您的代码中，您从未执行过查询。只在字符串中创建它。

if (mysqli_query ($conn, $sql)) {
    $sql= "UPDATE page_tracking SET count=count+1 where name= "index.php")";
    # execute the query
}

另外，不确定为什么这个松散else if没有条件：

else if {
    //Insert Query

您可能想要查看INSERT ... ON DUPLICATE KEY UPDATE语句，如果文件名是您的唯一键，则可以将整个代码减少为单个查询：

mysqli_query ($conn, "
    INSERT INTO page_tracking (name, count)
         VALUES ('index.php', 1)
    ON DUPLICATE KEY UPDATE count=count+1
");

Answer 2

1）不要在index.php周围使用double quotes使用single quotes。只需运行更新查询

    $sql = "SELECT * FROM page_tracking where name ="index.php"";
    $result =  mysqli_query ($conn, $sql);
    $num_rows = mysqli_num_rows($result);
    if ($num_rows) {
        $sql= "UPDATE page_tracking SET count=count+1 where name= 'index.php'";

    }else{
    $sql = "INSERT INTO page_tracking (name, count) VALUES ('index.php', '1')"; 
}

if (mysqli_query($conn, $sql)) {
    echo "Thanks for visiting! Your visit has been recorded";
} else {
    echo "Unfortunately we were unable to record your visit: " . $sql . "<br>" . mysqli_error($conn);
}

Answer 3

获取结果并检查其是否有记录。

  // Check to see if record exists
    $sql = "SELECT * FROM page_tracking where name ="index.php"";
    $query = mysqli_query ($conn, $sql);

    $result=mysqli_fetch_all($query,MYSQLI_ASSOC);
    if (count($result) > 0) {
        $sql= "UPDATE page_tracking SET count=count+1 where name="index.php")";
    }

    else {
    //Insert Query
    $sql = "INSERT INTO page_tracking (name, count)
    VALUES ('index.php', '1')"; 
    }

Answer 4

请试试这个。使用单引号而不是双引号。

$link = mysql_connect("localhost", $mysql_user, $mysql_password);
mysql_select_db($database, $link);

$result = mysql_query("SELECT * FROM page_tracking where name ='index.php'", $link);
$num_rows = mysql_num_rows($result);

if($num_rows==1){
  //Update Query
}else{
  //Insert Query
}

页数功能

4 个答案: