PHP-1.连接数据库

 1 <?php
 2 //数据库信息
 3 $servername = "localhost";
 4 $username = "root";
 5 $password = "****";
 6 $dbname="login";
 7 /*
 8  *  mysql_select_db('l');
 9  *  mysql_query('set names utf8');
10  */ 
11 //打开session
12 session_start();
13 //判断账号密码是否被赋值
14 if (isset($_POST['user']) && isset($_POST['pass'])) {
15     $user = $_POST['user'];
16     $pass = $_POST['pass'];
17     //建立一个数据库连接
18     $conn = mysql_connect($servername,$username,$password);
19     /* 测试
20      * if($conn)
21      *  echo "连接成功";
22      *  else die("连接失败".mysql_error());
23      */ }
24     //检查是否启动并给出提示
25     if (!$conn) {
26         die("connection failed:" . $conn->connect_error);
27     }
28     //指定一个数据库
29     $db_select=mysql_select_db($dbname,$conn);
30     //验证内容是否与数据库记录吻合
31     $sql_L = "SELECT * FROM l WHERE (username='$user') AND (password='$pass')";
32     //执行上面的sql语句并赋值给$r
33     $r = mysql_query($sql_L,$conn);
34     //将查到的结果数赋值$result
35     $result = mysql_num_rows($r);
36     //判断是否有对应记录
37     if ($result>0) {
38         echo "<script type='text/javascript'>alert('欢迎')</script>";
39     } else
40         echo "<script type='text/javascript'>alert('密码错误')</script>";
41     //关闭数据库连接
42     mysql_close($conn);
43 
44 
45 
46 ?>