Question

以下是2个表格：

类

            academic_year_id    student_id      standard

                    2               1               10
                    2               2               10
                    2               3               10
                    2               4               10
                    2               5               10
                    2               6               10
                    2               7               11 Science
                    2               8               11 Science

此处标准不是INT

学生

            student_id      roll_no         name            teacher_approval

                1               0       S Sumeet G                  1
                2               0       Nair Nikhil R               1
                3               0       Nayak Ankita R              0
                4               0       Rathod Ketan P              0
                5               0       Patel Vishal D              1
                6               0       Patel Jignesh R             0
                7               0       Prajapati Bhavesh A         1
                8               0       Shah Harsh N                1

我想做什么：

当教师选择标准时 - ＆gt; 10并按下“分配卷号”按钮

我想要所有第10个标准的学生按名称顺序给予滚动，并且由老师批准，即teacher_approval ='1'

所以我的学生表如下：

学生

            student_id      roll_no         name            teacher_approval

                1               3       S Sumeet G                  1
                2               1       Nair Nikhil R               1
                3               0       Nayak Ankita R              0
                4               0       Rathod Ketan P              0
                5               2       Patel Vishal D              1
                6               0       Patel Jignesh R             0
                7               0       Prajapati Bhavesh A         1
                8               0       Shah Harsh N                1

我到目前为止尝试了以下代码：

$standard = $_POST['standard']

SET @incr = 0

     UPDATE
        student AS st
        JOIN
        (   SELECT * FROM
        classes AS classes
        WHERE standard = '".$standard."'
        ) AS tmp
        ON tmp.student_id = st.id
        SET
        st.roll_no = @incr:=@incr+1 
        WHERE st.teacher_approval = '1'
        ORDER BY st.name ASC

但是它给了我一个错误：错误地使用了更新和订单

有类似经历的人吗？任何帮助，将不胜感激。感谢。

Answer 1

在MySql中，当使用多个表时，您不能直接将ORDER BY作为UPDATE的一部分（请参阅此link）。试试这个：

UPDATE student AS table1
        INNER JOIN (
        SELECT st.student_id, st.roll_no, st.name, st.teacher_approval
        FROM student AS st
            JOIN (
            SELECT * FROM
            classes AS cl
            WHERE cl.standard = '".$standard."'
            ) AS tmp
            ON tmp.student_id = st.student_id
            WHERE st.teacher_approval = '1'
            ORDER BY st.name ASC
        ) AS table2 
        ON table2.student_id = table1.student_id
    SET table1.roll_no = @incr:=@incr+1

希望这有帮助。

mysql根据另一个表将序列更新到一个表中

1 个答案: