How to implement SQL injection prevention in PHP?

php method to implement SQL injection prevention: 1. execute parameter method, the code is [$stmt->execute(array($_POST[$j], $_POST[$i])]; 2. bindParam binds parameters, the code is [$stmt->bindPara("")].

php implements sql anti-injection method:

Method 1: execute substitute parameters

<?php
if(count($_POST)!= 0) {
  $host = &#39;aaa&#39;;
  $database = &#39;bbb&#39;;
  $username = &#39;ccc&#39;;
  $password = &#39;***&#39;;
  $num = 0;
  $pdo = new PDO("mysql:host=$host;dbname=$database", $username, $password);//创建一个pdo对象
  foreach ($_POST as $var_Key => $var_Value) {
    //获取POST数组最大值
    $num = $num + 1;
  }
  //下标为i的数组存储的是商品id, 下标为j数组的存储的是此商品的库存
  for($i=0;$i<$num;$i=$i+2)
  {
    //库存下标
    $j = $i+1;
    //判断传递过来的数据合法性
    if(is_numeric(trim($_POST[$i])) && is_numeric(trim($_POST[$j]))){
      //禁用prepared statements的仿真效果
      $pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
      //查询数据库中是否存在该ID的商品
      //当调用 prepare() 时，查询语句已经发送给了数据库服务器，此时只有占位符 ? 发送过去，没有用户提交的数据
      $stmt = $pdo->prepare("select good_id from delphi_test_content WHERE good_id = ?");
      //当调用到 execute()时，用户提交过来的值才会传送给数据库，他们是分开传送的，两者独立的，SQL攻击者没有一点机会。
      $stmt->execute(array($_POST[$i]));
      //返回查询结果
      $count = $stmt->rowCount();
      //如果本地数据库存在该商品ID和库存记录，就更新该商品的库存
      if($count != 0)
      {
        $stmt = $pdo->prepare("update delphi_test_content set content = ? WHERE good_id = ?");
        $stmt->execute(array($_POST[$j], $_POST[$i]));
      }
      //如果本地数据库没有该商品ID和库存记录，就新增该条记录
      if($count == 0)
      {
        $stmt = $pdo->prepare("insert into delphi_test_content (good_id,content) values (?,?)");
        $stmt->execute(array($_POST[$i], $_POST[$j]));
      }
    }
  }
  $pdo = null;
  //关闭连接
}
?>

Method 2: bindParam binding parameters

<?php
if(count($_POST)!= 0) {
  $host = &#39;aaa&#39;;
  $database = &#39;bbb&#39;;
  $username = &#39;ccc&#39;;
  $password = &#39;***&#39;;
  $num = 0;
  $pdo = new PDO("mysql:host=$host;dbname=$database", $username, $password);//创建一个pdo对象
  foreach ($_POST as $var_Key => $var_Value) {
    //获取POST数组最大值
    $num = $num + 1;
  }
  //下标为i的数组存储的是商品id, 下标为j数组的存储的是此商品的库存
  for($i=0;$i<$num;$i=$i+2)
  {
    //库存下标
    $j = $i+1;
    //判断传递过来的数据合法性(此数据为商品编号以及库存，严格来说字符串全是由数字组成的)
    if(is_numeric(trim($_POST[$i])) && is_numeric(trim($_POST[$j]))){
      //查询数据库中是否存在该ID的商品
      $stmt = $pdo->prepare("select good_id from delphi_test_content WHERE good_id = ?");
      $stmt->execute(array($_POST[$i]));
      $stmt->bindParam(1,$_POST[$i]);
      $stmt->execute();
      //返回查询结果
      $count = $stmt->rowCount();
      //如果本地数据库存在该商品ID和库存记录，就更新该商品的库存
      if($count != 0)
      {
        $stmt = $pdo->prepare("update delphi_test_content set content = ? WHERE good_id = ?");
        $stmt->execute(array($_POST[$j], $_POST[$i]));
        $stmt->bindParam(1,$_POST[$j]);
        $stmt->bindParam(2,$_POST[$i]);
        $stmt->execute();
      }
      //如果本地数据库没有该商品ID和库存记录，就新增该条记录
      if($count == 0)
      {
        $stmt = $pdo->prepare("insert into delphi_test_content (good_id,content) values (?,?)");
        $stmt->bindParam(1,$_POST[$i]);
        $stmt->bindParam(2,$_POST[$j]);
        $stmt->execute();
      }
    }
  }
  $pdo = null;
  //关闭连接
}
?>

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