在SELECTION语句的非对象上调用成员函数bind_param（）

Question

我使用以下代码段从学生表中选择行数。但它显示错误＆＃34;致命错误：在非对象上调用成员函数bind_param（）＆＃34;。在我的桌子＆＃39; stacyear＆＃39;是VARCHAR，＆＃39; courseid＆＃39;是TINY INT。

$stmt = $mysqli->prepare("SELECT count (*) FROM students WHERE stacyear = ? and courseid = ?");
$stmt->bind_param('si', $acyear, $courseid); 
$stmt->execute();    
$stmt->store_result();
$stmt->bind_result($utype);
$stmt->fetch();

Answer 1

您不能在COUNT和(*)之间留出空格。改为

$stmt = $mysqli->prepare("SELECT count(*) FROM students WHERE stacyear = ? and courseid = ?");