使用PHP函数执行MySQL操作

PHP可以使用一些内置函数来执行MySQL数据库操作。以下是一些重要的MySQL操作函数及其用法。

1. mysqli_connect()

mysqli_connect()函数用于连接MySQL数据库。以下是连接MySQL数据库的示例代码：

$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// 创建连接
$conn = mysqli_connect($servername, $username, $password, $dbname);

// 检查连接是否成功
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}
echo "连接成功";

2. mysqli_query()

mysqli_query()函数用于执行SQL查询。以下是查询数据库中所有记录的示例代码：

$sql = "SELECT * FROM MyGuests";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    // 输出数据
    while($row = mysqli_fetch_assoc($result)) {
        echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
    }
} else {
    echo "0 结果";
}

3. mysqli_fetch_assoc()

mysqli_fetch_assoc()函数用于从结果集中取得一行作为关联数组。以下是使用mysqli_fetch_assoc()函数获取查询结果的示例代码：

$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    // 输出数据
    while($row = mysqli_fetch_assoc($result)) {
        echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
    }
} else {
    echo "0 结果";
}

4. mysqli_fetch_array()

mysqli_fetch_array()函数用于从结果集中取得一行作为关联数组、数字数组或二者兼有的数组。以下是使用mysqli_fetch_array()函数获取查询结果的示例代码：

$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    // 输出数据
    while($row = mysqli_fetch_array($result)) {
        echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
    }
} else {
    echo "0 结果";
}

5. mysqli_num_rows()

mysqli_num_rows()函数用于获取查询结果集中的行数。以下是使用mysqli_num_rows()函数获取查询结果中行数的示例代码：

$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = mysqli_query($conn, $sql);

echo "结果集中行数为: " . mysqli_num_rows($result);

6. mysqli_insert_id()

mysqli_insert_id()函数用于获取最后插入的记录的ID号。以下是使用mysqli_insert_id()函数获取最后插入记录ID的示例代码：

$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', 'john@example.com')";

if (mysqli_query($conn, $sql)) {
    $last_id = mysqli_insert_id($conn);
    echo "新记录插入成功，插入ID为: " . $last_id;
} else {
    echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}

7. mysqli_real_escape_string()

mysqli_real_escape_string()函数用于过滤SQL语句中的特殊字符。以下是使用mysqli_real_escape_string()函数防止SQL注入的示例代码：

$firstname = mysqli_real_escape_string($conn, $_POST['firstname']);
$lastname = mysqli_real_escape_string($conn, $_POST['lastname']);
$email = mysqli_real_escape_string($conn, $_POST['email']);

$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('$firstname', '$lastname', '$email')";

if (mysqli_query($conn, $sql)) {
    echo "新记录插入成功";
} else {
    echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}

mysqli_close($conn);

以上是一些重要的PHP函数用于执行MySQL操作的示例代码，可以用于实现与MySQL数据库的交互操作。