PHP获取行数

Question

$count = mysql_query("SELECT COUNT(id) FROM users");

echo $count;

这不起作用。错误消息资源ID未知＃21 如何解决这个问题？

Answer 1

您应该使用fetchColumn()

$count = $db->query("SELECT COUNT(id) FROM users");

应该是

$count = $db->query("SELECT COUNT(id) FROM users")->fetchColumn();

echo $count; //Returns number of rows

Answer 2

使用此mysql_num_rows

$sql=mysql_query("SELECT COUNT(id) FROM users");
$count= mysql_num_rows($sql);
echo $count ;