带有 PDO 函数的 Php Sum 和 mysql

Question

PDO 的新手...我正在尝试求和，但这里出现错误是我的代码

function test_score_month($student_id){
    global $host, $dbname, $user, $pass;

    $DBH = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);
    $STH = $DBH->query("SELECT SUM(score), SUM(score_from) FROM school_test_report
    WHERE 
     school_test_report.test_date >= last_march() and school_test_report.test_date <= march()" );
    $STH->setFetchMode(PDO::FETCH_BOTH);
    return $STH;
}

输出是

$student_id = test_score_month($name);
echo $student_id['SUM(score)'];

但出现错误

Call to a member function setFetchMode() on a non-object in

我试过了

$STH->setFetchMode(PDO::FETCH_ASSOC);

还是一样的错误

Answer 1

您的查询有语法错误:

WHERE 
    and

您还确定您的数据库中有 march() 和 last_march() 函数吗？

[+] 总是在查询数据库后检查错误:

if($STH){
 // do your stuff
}else{
 die($DBH->errorInfo()); // see the error
}

参见 http://www.php.net/manual/en/pdo.errorinfo.php