php5的程序升级到php7后数据库不可用，修改代码替换mysqli函数的方法，简易升级步骤

小樱

php5升级前

1.                 mysql_connect ($ip, $dbuser, $dbpass)or die("无法连接到数据库: ".mysql_error());
   
2.                 mysql_select_db($dbname) or die(mysql_error());
   
3.                 $md5pass = md5($pass);
   
4.                 $checkuser = mysql_query("SELECT * FROM user WHERE name='$user' and password='$md5pass'");
   
5.                 @$username_exist = mysql_num_rows($checkuser);
   
6.                 if($username_exist >= 1)

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php7修改后

1.                 $link = mysqli_connect ($ip, $dbuser, $dbpass, $dbname);
   
2.                 if (mysqli_connect_errno($link))
   
3.                 {
   
4.                 echo "无法连接到数据库: " . mysqli_connect_error();
   
5.                 }
   
6.                 $md5pass = md5($pass);
   
7.                 $checkuser = mysqli_query($link,"SELECT * FROM user WHERE name='$user' and password='$md5pass'");
   
8.                 @$username_exist = mysqli_fetch_row($checkuser);
   
9.                 if($username_exist >= 1)

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else之类语句完毕用完后记得随手关闭数据库

1. mysqli_close($link);

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