PHP mysqli real_escape_string() 函数

定义和用法

real_escape_string() / mysqli_real_escape_string() 函数转义字符串中的特殊字符，以便在 SQL 查询中使用，同时考虑连接的当前字符集。

此函数用于创建可在 SQL 语句中使用的合法 SQL 字符串。假设我们有以下代码：

<?php

$lastname = "D'Ore";

$sql="INSERT INTO Persons (LastName) VALUES ('$lastname')";

// 此查询将失败，因为我们没有转义 $lastname
if (!$mysqli -> query($sql)) {
  printf("%d Row inserted.\n", $mysqli->affected_rows);
}

?>

实例

例子 1 - 面向对象风格

转义字符串中的特殊字符：

<?php
$mysqli = new mysqli("localhost","my_user","my_password","my_db");

if ($mysqli -> connect_errno) {
  echo "Failed to connect to MySQL: " . $mysqli -> connect_error;
  exit();
}

// 转义特殊字符（如果有）
$firstname = $mysqli -> real_escape_string($_POST['firstname']);
$lastname = $mysqli -> real_escape_string($_POST['lastname']);
$age = $mysqli -> real_escape_string($_POST['age']);

$sql="INSERT INTO Persons (FirstName, LastName, Age) VALUES ('$firstname', '$lastname', '$age')";

if (!$mysqli -> query($sql)) {
  printf("%d Row inserted.\n", $mysqli->affected_rows);
}

$mysqli -> close();
?>

例子 2 - 过程式风格

转义字符串中的特殊字符：

<?php
$con = mysqli_connect("localhost","my_user","my_password","my_db");

if (mysqli_connect_errno()) {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  exit();
}

// 转义特殊字符（如果有）
$firstname = mysqli_real_escape_string($con, $_POST['firstname']);
$lastname = mysqli_real_escape_string($con, $_POST['lastname']);
$age = mysqli_real_escape_string($con, $_POST['age']);

$sql="INSERT INTO Persons (FirstName, LastName, Age) VALUES ('$firstname', '$lastname', '$age')";

if (!mysqli_query($con, $sql)) {
  printf("%d Row inserted.\n", mysqli_affected_rows($con));
}

mysqli_close($con);
?>

语法

面向对象风格：

$mysqli -> real_escape_string(escapestring)

过程式风格：

mysqli_real_escape_string(connection, escapestring)

技术细节