Question

我有用于选择和打印值的代码。 mysql_numn_rows返回null：/

<?php 
mysql_connect('localhost','root',''); 
mysql_select_db("db2517"); 



$username = "Cristoforo"; 
$query = mysql_query("SELECT * users WHERE username='$username' "); 

$numberOfRows = mysql_num_rows($query); 
echo "num: $numberOfRows"; 


?> 

Answer 1

更好地使用的mysqli或PDO，而不是你在查询错过 from mysql.here

所以你的查询应该是

$query = mysql_query("SELECT * from users WHERE username='$username' "); 

Answer 2

首先，我想建议你用户PDO或MYQLI

在你查询你已经错过了from所以替换查询：

从

$query = mysql_query("SELECT * users WHERE username='$username' "); 

要

$query = mysql_query("SELECT * from users WHERE username='$username' ");