MYSQL和条件不起作用

Question

我已经编写了代码来获取mysql_num_rows（）但总是给出输出零

$myc= "SELECT * FROM scores WHERE user_id=$userid AND quiz_id=$myqid";
$completed=mysql_query($myc,$kpsctuts->connect) or  die('MySql Error!  ' . mysql_error());
echo "<br/> row count:  ".mysql_num_rows($completed);
if (mysql_num_rows($completed) > 0) {
exit;
}

Answer 1

尝试使用此方法从mysql服务器获取数据。

$connect=@mysql_connect("localhost","root","password");
mysql_select_db("db_name",$connect);

$myc= "SELECT * FROM scores WHERE user_id=$userid AND quiz_id=$myqid";
$completed=mysql_query($myc);
echo mysql_error();

echo "<br/> row count:  ".mysql_num_rows($completed);
if (mysql_num_rows($completed) > 0) {
exit;
}

这仅基于mysql_query，它有助于在执行查询之前建立连接