在课程教学任务表(tbTeachingTasks)的TaskID,CourseID,TeacherID,StudentID字段上创建名为idxtbTeachingTasks的普通索引的代码
时间: 2024-03-27 18:37:11 浏览: 13
以下是在MySQL数据库中创建名为idxtbTeachingTasks的普通索引的SQL代码:
```
CREATE INDEX idxtbTeachingTasks ON tbTeachingTasks(TaskID, CourseID, TeacherID, StudentID);
```
这将在tbTeachingTasks表的TaskID、CourseID、TeacherID和StudentID四个字段上创建一个普通索引,名为idxtbTeachingTasks。
相关问题
按如下表数据结构完成数据表的创建。 1)院系表tbDepartment 2)专业表tbMajor 3)教师表tbTeacher 4)班级表tbClass 5)学生表tbStudent 6)课程信息表tbCourse 7)课程教学任务表tbTeachingTasks 8)成绩表tbScore
以下是创建这些表的SQL语句:
1)院系表tbDepartment
```SQL
CREATE TABLE tbDepartment (
DepartmentID INT PRIMARY KEY,
DepartmentName VARCHAR(50),
DeanName VARCHAR(50)
);
```
2)专业表tbMajor
```SQL
CREATE TABLE tbMajor (
MajorID INT PRIMARY KEY,
MajorName VARCHAR(50),
DepartmentID INT,
FOREIGN KEY (DepartmentID) REFERENCES tbDepartment(DepartmentID)
);
```
3)教师表tbTeacher
```SQL
CREATE TABLE tbTeacher (
TeacherID INT PRIMARY KEY,
TeacherName VARCHAR(50),
DepartmentID INT,
FOREIGN KEY (DepartmentID) REFERENCES tbDepartment(DepartmentID)
);
```
4)班级表tbClass
```SQL
CREATE TABLE tbClass (
ClassID INT PRIMARY KEY,
ClassName VARCHAR(50),
MajorID INT,
FOREIGN KEY (MajorID) REFERENCES tbMajor(MajorID)
);
```
5)学生表tbStudent
```SQL
CREATE TABLE tbStudent (
StudentID INT PRIMARY KEY,
StudentName VARCHAR(50),
ClassID INT,
FOREIGN KEY (ClassID) REFERENCES tbClass(ClassID)
);
```
6)课程信息表tbCourse
```SQL
CREATE TABLE tbCourse (
CourseID INT PRIMARY KEY,
CourseName VARCHAR(50),
Credit FLOAT,
DepartmentID INT,
FOREIGN KEY (DepartmentID) REFERENCES tbDepartment(DepartmentID)
);
```
7)课程教学任务表tbTeachingTasks
```SQL
CREATE TABLE tbTeachingTasks (
TaskID INT PRIMARY KEY,
CourseID INT,
TeacherID INT,
ClassID INT,
FOREIGN KEY (CourseID) REFERENCES tbCourse(CourseID),
FOREIGN KEY (TeacherID) REFERENCES tbTeacher(TeacherID),
FOREIGN KEY (ClassID) REFERENCES tbClass(ClassID)
);
```
8)成绩表tbScore
```SQL
CREATE TABLE tbScore (
ScoreID INT PRIMARY KEY,
TaskID INT,
StudentID INT,
Score FLOAT,
FOREIGN KEY (TaskID) REFERENCES tbTeachingTasks(TaskID),
FOREIGN KEY (StudentID) REFERENCES tbStudent(StudentID)
);
```
mysql 语句,删除info表的某些数据,这些数据满足的条件为 info表taskid字段 在task表查询为空
可以使用如下的 MySQL 语句来删除 `info` 表中满足 `taskid` 字段在 `task` 表查询结果为空的数据:
```
DELETE FROM info
WHERE taskid NOT IN (SELECT taskid FROM task)
```
这个语句使用了子查询来查询 `task` 表中所有的 `taskid`,然后删除 `info` 表中 `taskid` 不在这个列表中的所有数据。这里假设 `task` 表中的 `taskid` 字段与 `info` 表中的 `taskid` 字段是相同的,如果不是的话需要根据实际情况进行修改。