PHP - 获取最后插入的ID

Question

我知道这个问题已经被回答了很多次。我尝试了这里的一些解决方案，但都没有起作用。我没有使用任何 PHP 框架。

我正在执行一个插入操作，并且我想要获取插入行的 ID。

这是我的代码：

$qry="INSERT INTO tablename(content) VALUES('".$content."')";
setData($qry);

setData() 是一个用户定义的函数，用于执行插入操作。

//for data submit
function setData($qry)
{
    $obj=new DBCon();
    $res=$obj->submitQuery($qry);
    return $res;
}

//fetches result
function getData($qry)
{
    $obj=new DBCon();
    $res=$obj->selectQuery($qry);
    return $res;
}

这是我为建立数据库连接所创建的类：

class DBCon
    {   
        private function getConnection()
        {   
                               // hostname,   username,     password,   database
            $con=mysqli_connect("localhost","root","","dbname")OR die('Could not Connect the Database');        
            return $con;
        }

        public function closeCon()
        {
            mysqli_close($con);
        }

        public function submitQuery($qry)
        {
            $result=0;
            $con=$this->getConnection();
            $result=mysqli_query($con,$qry);
            return $result;
        }

        public function selectQuery($qry)
        {
            $con=$this->getConnection();
            $res=mysqli_query($con,$qry);
            return $res;
        }
    }

为了获取最后插入的id，我编写了以下查询语句，但没有返回任何结果：

SELECT LAST_INSERT_ID() FROM tablename

有没有其他方法可以获得这个？

- version 2

---

尝试在插入查询后使用 $id = last_insert_id(); - Snopzer

也许有趣？http://php.net/manual/zh/mysqli.insert-id.php，即 $lastId = mysqli_insert_id($connection);。 - Ryan Vincent

你并没有分享任何尝试的代码，所以很难说你做错了什么或者为什么你认为需要手动运行 SELECT LAST_INSERT_ID() FROM tablename。我们只能猜测，我的猜测是你没有在插入后立即在同一连接中获取ID。 - Álvaro González

Answer 1

LAST_INSERT_ID() 只返回由 MySQL 服务器自动生成的 AUTO_INCREMENT 列的值；当您插入一个特定的值时，不会进行自动生成，LAST_INSERT_ID() 不会返回任何值。

尝试使用：$con->insert_id;

- Mohammad Fareed

---

这段代码不会产生任何结果 @Mohammad Fareed - version 2

你的表格是否有带有自增主键的ID相关列？ - Snopzer

@Amelia Earheart 现在有任何结果了吗？ - Snopzer

是的，自动递增字段已经存在。@Mohammad Fareed - version 2

尝试使用 $conn->insert_id; - Snopzer

db::getInstance()->lastInsertId(); - user1026996

Answer 2

尝试这种方式。

$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('First Name', 'Last Name', '[e-mail]')";

if ($conn->query($sql) === TRUE) {
    $last_id = $conn->insert_id;
    echo "New record created successfully. Last inserted ID is: " . $last_id;
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

- Hiren Makwana

---

含糊不清的问题在于无法确定一个使用示例（据原帖所述已尝试但不喜欢）是否解决了问题。 - Álvaro González

Answer 3

MySQLi面向对象

 <?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', '[e-mail]')";

if ($conn->query($sql) === TRUE) {
    $last_id = $conn->insert_id;
    echo "New record created successfully. Last inserted ID is: " . $last_id;
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

$conn->close();
?>

MySQLi过程化编程

     <?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);
// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', '[e-mail]')";

if (mysqli_query($conn, $sql)) {
    $last_id = mysqli_insert_id($conn);
    echo "New record created successfully. Last inserted ID is: " . $last_id;
} else {
    echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}

mysqli_close($conn);
?> 

PDO

 <?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $sql = "INSERT INTO MyGuests (firstname, lastname, email)
    VALUES ('John', 'Doe', '[e-mail]')";
    // use exec() because no results are returned
    $conn->exec($sql);
    $last_id = $conn->lastInsertId();
    echo "New record created successfully. Last inserted ID is: " . $last_id;
    }
catch(PDOException $e)
    {
    echo $sql . "<br>" . $e->getMessage();
    }

$conn = null;
?> 

- Dhiraj Thakur

Answer 4

 $last_id = $conn->insert_id;

- user7978672

---

你应该解释你的代码是做什么的。在SO上，只有代码的答案通常会被标记为低质量。 - Shakti Phartiyal