Mysql 如何为学生成绩更新连接表中的行
我又来了。 非常感谢你的帮助 这是我的老问题,关于如何在连接表中选择和显示学生的成绩 我成功地做到了,但是现在我在更新连接表中的等级时遇到了问题 这是我的示例表Mysql 如何为学生成绩更新连接表中的行,mysql,sql,database,vb.net,phpmyadmin,Mysql,Sql,Database,Vb.net,Phpmyadmin,我又来了。 非常感谢你的帮助 这是我的老问题,关于如何在连接表中选择和显示学生的成绩 我成功地做到了,但是现在我在更新连接表中的等级时遇到了问题 这是我的示例表 "student" ----------------------- |studentID | FullName | ----------------------- |1234 | John | |1235 | Michael | |1236 | Bryce | "sub
"student"
-----------------------
|studentID | FullName |
-----------------------
|1234 | John |
|1235 | Michael |
|1236 | Bryce |
"subject_bsit"
-----------------------------------
|subject_id| subject_name |grade |
-----------------------------------
| 1 | Programming | 3 |
| 2 | Networking | 2.5 |
| 3 | Algorithm | 1.75|
| 4 | Physical Educ | 2 |
This is the Junction table to connect the
two now.
"student_subject"
----------------------------
| student_id | subject_id |
----------------------------
| 1235 | 1 |
| 1235 | 2 |
| 1235 | 3 |
| 1234 | 1 |
这是我提出的问题。
这是一个例子,我试图更新科目id=1的学生id 1235的成绩
更新3:
sql = "UPDATE student_subject " & _
" INNER JOIN subject_bsit " & _
" ON subject_bsit.subject_id = student_subject.sub_id " & _
" SET grade = 1 " & _
" where student_subject.student_id='" & Txtbox.Text & "' AND student_subject.sub_id = 1"
&Txtbox.Text&是用户输入studentid的地方,请不要介意。非常感谢您,我正在使用visual Studio vb.net
这正是我得到的错误
SQL语法有错误;检查相应的手册
您的MySQL服务器版本提供了正确的语法,可在“FROM”附近使用
学生\u科目内部联接科目\u bsit ON subject\u bsit.subject\u id=
一号线的学生
您的查询不稳定,应该如下所示
UPDATE student_subject
INNER JOIN subject_bsit
ON subject_bsit.subject_id = student_subject.sub_id
SET grade=?
where student_subject.student_id='" & Txtbox.Text & "' AND student_subject.sub_id = 1
您的查询不稳定,应该如下所示
UPDATE student_subject
INNER JOIN subject_bsit
ON subject_bsit.subject_id = student_subject.sub_id
SET grade=?
where student_subject.student_id='" & Txtbox.Text & "' AND student_subject.sub_id = 1
首先,你不更新学生课程。 由于科目表中没有“学生id”列,因此无法将分数与学生关联 更新主题信息 设置等级=@grade 其中subject\u ID=@subject\u ID 这将完成同样的事情 这就是我建议的模式 学生
+-------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+----------------+
| studentID | int(11) | NO | PRI | NULL | auto_increment |
| studentName | varchar(100) | NO | | NULL | |
+-------------+--------------+------+-----+---------+----------------+
+-----------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| studentID | int(11) | NO | PRI | NULL | |
| subjectID | int(11) | NO | PRI | NULL | |
| grade | decimal(3,2) | YES | | NULL | |
+-----------+--------------+------+-----+---------+-------+
+-------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+----------------+
| subjectID | int(11) | NO | PRI | NULL | auto_increment |
| subjectName | varchar(100) | NO | | NULL | |
+-------------+--------------+------+-----+---------+----------------+
等级
+-------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+----------------+
| studentID | int(11) | NO | PRI | NULL | auto_increment |
| studentName | varchar(100) | NO | | NULL | |
+-------------+--------------+------+-----+---------+----------------+
+-----------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| studentID | int(11) | NO | PRI | NULL | |
| subjectID | int(11) | NO | PRI | NULL | |
| grade | decimal(3,2) | YES | | NULL | |
+-----------+--------------+------+-----+---------+-------+
+-------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+----------------+
| subjectID | int(11) | NO | PRI | NULL | auto_increment |
| subjectName | varchar(100) | NO | | NULL | |
+-------------+--------------+------+-----+---------+----------------+
两个外键
+-------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+----------------+
| studentID | int(11) | NO | PRI | NULL | auto_increment |
| studentName | varchar(100) | NO | | NULL | |
+-------------+--------------+------+-----+---------+----------------+
+-----------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| studentID | int(11) | NO | PRI | NULL | |
| subjectID | int(11) | NO | PRI | NULL | |
| grade | decimal(3,2) | YES | | NULL | |
+-----------+--------------+------+-----+---------+-------+
+-------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+----------------+
| subjectID | int(11) | NO | PRI | NULL | auto_increment |
| subjectName | varchar(100) | NO | | NULL | |
+-------------+--------------+------+-----+---------+----------------+
等级
+-------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+----------------+
| studentID | int(11) | NO | PRI | NULL | auto_increment |
| studentName | varchar(100) | NO | | NULL | |
+-------------+--------------+------+-----+---------+----------------+
+-----------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| studentID | int(11) | NO | PRI | NULL | |
| subjectID | int(11) | NO | PRI | NULL | |
| grade | decimal(3,2) | YES | | NULL | |
+-----------+--------------+------+-----+---------+-------+
+-------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------+------+-----+---------+----------------+
| subjectID | int(11) | NO | PRI | NULL | auto_increment |
| subjectName | varchar(100) | NO | | NULL | |
+-------------+--------------+------+-----+---------+----------------+
两个外键