php - 使用 PHP/MySQL 计算百分比

Question

我正在尝试计算已完成在线成绩簿作业的学生人数，但我无法计算出代码...

    // SELECT THE TOTAL
$gettotal = "SELECT enroll FROM student_course WHERE classID = $classID";
$showtotal = @mysqli_query ($dbc, $gettotal); // Run the query.

//THIS IS LINE 108
$numtotal = mysql_num_rows($showtotal);

echo '$numtotal';

// SELECT THOSE PASSED
$getpassed = "SELECT entry FROM grades WHERE classID = $classID AND test_result >= 80";
$showpassed = @mysqli_query ($dbc, $getpassed); // Run the query.

$numpassed = mysql_num_rows($showpassed);

//THIS IS LINE 117
echo '$numpassed';

        // PERFORM THE PERCENTAGE FUNCTION

        function percent($numpassed, $numtotal) {
            $count1 = $numpassed / $numtotal;
            $count2 = $count1 * 100;
            $count = number_format($count2, 0);
            echo $count;
        }

//THIS IS LINE 124
        percent($numpassed, $numtotal);

我收到以下错误:

警告:mysql_num_rows():第 108 行提供的参数不是有效的 MySQL 结果资源总计 $num警告:mysql_num_rows():第 117 行提供的参数不是有效的 MySQL 结果资源$numpassed警告:第 124 行中除以零0

Answer 1

好吧 - 虽然我感谢大家关心删除@...但没有人注意到问题出在使用mysqli_query，然后使用mysql_num_rows。需要将其更改为 mysqli_num_rows。

谢谢:)