Question

我目前正在开发一个PHP应用程序，它对MySQL的一组结果进行排名，然后在网页上显示它们。我制作了三个MySQLi查询，然后以排名显示结果。一切似乎都很好但在某些时候（没有常规模式），显示的结果有时会显示0作为第一个等级而不是1，有些则显示为1。

我已经尝试调试过去一个月的代码，但没有进展，我不得不重写在不同场合完全执行查询的代码，但零0问题仍然存在。

以下是我的代码：

这是第一部分：

$sql0       = "SET @rank = 0, @prev_val3 = NULL;";
$pull_report_details5 = "SELECT rank, score, student_number, subject_name, gender FROM (
                    SELECT @rank := IF(@prev_val3=score,@rank,@rank+1) AS rank, @prev_val3 := score AS score, student_number, subject_name, gender
                    FROM uploaded_results WHERE `subject_name` = '$subject_name' ORDER BY score DESC
                    ) as result";
mysqli_query($dbc, $sql0)or mysql_error();
$push_pull_report_details5 = mysqli_query($dbc, $pull_report_details5)or die("Error pulling report details");

第二部分：

$sql1       = "SET @rank2 = 0, @prev_val2 = NULL;";
$pull_report_details3 = "SELECT rank2, score, student_number, subject_name, gender FROM (
                    SELECT @rank2 := IF(@prev_val2=score,@rank2,@rank2+1) AS rank2, @prev_val2 := score AS score, student_number, subject_name, gender
                    FROM uploaded_results WHERE `subject_name` = '$subject_name' AND `gender` = 'Male' ORDER BY score DESC
                    ) as result";
mysqli_query($dbc, $sql1)or mysql_error();
$push_pull_report_details3 = mysqli_query($dbc, $pull_report_details3)or die(mysqli_error($dbc)."failure");

第三部分：

$sql2       = "SET @rank1 = 0, @prev_val = NULL;";
$pull_report_details4 = "SELECT rank1, score, student_number, subject_name, gender FROM (
                    SELECT @rank1 := IF(@prev_val=score,@rank1,@rank1+1) AS rank1, @prev_val := score AS score, student_number, subject_name, gender
                    FROM uploaded_results WHERE `subject_name` = '$subject_name' AND `gender` = 'Female' ORDER BY score DESC
                    ) as result2";
mysqli_query($dbc, $sql2)or mysql_error();
$push_pull_report_details4 = mysqli_query($dbc, $pull_report_details4)or die("Error pulling report details");

最后，我在三个不同的表上显示三个查询。

PHP MYSQL排名第一等级为零

0 个答案: