<?php
  $mysqli = new mysqli("hostname", "dbusername", "dbpassword", "dbname");

   /* check connection */
   if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
     exit();
   }

  if ($result = $mysqli->query("SELECT count(*) cc FROM tablename")) {

     /* fetch the first row as result */
     $row = $result->fetch_assoc();

    printf("Result set has %d rows.\n", $row['cc']);

   /* close result set */
    $result->close();
 }

 /* close connection */
 $mysqli->close();
?>

其实这是一个常见的问题，你可以在任何地方找到答案。

In fact it's a common question you can find the answer anywhere.

例如， http://php.net/手动/ en / mysqli-result.num-rows.php

您可以将此问题分为两个

You could separate this problem in to two

1. 我想知道如何连接到mysql。


2. 我想知道如何写sql指令。