php mysql_real_escape_string()函数

mysql教程_real_escape_string() 函数转义 SQL 语句中使用的字符串中的特殊字符。

下列字符受影响：

x00
n
r

'
"
x1a
如果成功，则该函数返回被转义的字符串。如果失败，则返回 false。

语法
mysql_real_escape_string(string,connection)参数 描述
string 必需。规定要转义的字符串。
connection 可选。规定 MySQL 连接。如果未规定，则使用上一个连接。
实例

php教程
  function opendatabase ($host,$user,$pass) {
    try {
      if ($db = mysql_connect ($host,$user,$pass)){
        return $db;
      } else {
        throw new exception ("Sorry, could not connect to mysql.");
      }
    } catch (exception $e) {
      echo $e->getmessage ();
    }
  }
 
  function selectdb ($whichdb, $db){
    try {
      if (!mysql_select_db ($whichdb,$db)){
        throw new exception ("Sorry, database could not be opened.");
      }
    } catch (exception $e) {
      echo $e->getmessage();
    }
  }
  function closedatabase ($db){
    mysql_close ($db);
  }
  $db = opendatabase ("localhost","root","");
  selectdb ("mydatabase",$db);
  $_POST['user'] = "myname";
  $_POST['pass'] = "mypassword";
 
  function validatelogin ($user,$pass){
    mysql_real_escape_string ($user);
    mysql_real_escape_string ($pass);
    $thequery = "SELECT * FROM userlogin WHERE username='$user' AND password='$pass'";
    if ($aquery = mysql_query ($thequery)){
      if (mysql_num_rows ($aquery) > 0){
        return true;
      } else {
        return false;
      }
    } else {
      echo mysql_error();
    }
  }
 
  if (validatelogin ($_POST['user'],$_POST['pass'])){
    echo "You have successfully logged in.";
  } else {
    echo "Sorry, you have an incorrect username and/or password.";
  }
 
  closedatabase ($db);
 
?>