写一份毕业生信息管理系统约束条件的增加,删除,修改的sqlsever数据库代码
时间: 2024-05-31 19:07:15 浏览: 16
增加约束条件:
ALTER TABLE 表名
ADD CONSTRAINT 约束名 CONSTRAINT_TYPE (列名) ;
例如:
ALTER TABLE Students
ADD CONSTRAINT PK_Students PRIMARY KEY (StudentID);
删除约束条件:
ALTER TABLE 表名
DROP CONSTRAINT 约束名;
例如:
ALTER TABLE Students
DROP CONSTRAINT PK_Students;
修改约束条件:
ALTER TABLE 表名
DROP CONSTRAINT 约束名;
ALTER TABLE 表名
ADD CONSTRAINT 新约束名 CONSTRAINT_TYPE (列名) ;
例如:
ALTER TABLE Students
DROP CONSTRAINT PK_Students;
ALTER TABLE Students
ADD CONSTRAINT UK_Students UNIQUE (StudentName);
相关问题
写一份毕业生信息管理系统的sqlsever数据库的增加,删除,修改的代码
如果数据过大,线程不够用,可以采取以下措施:
1. 分批处理数据:将大数据集分成多个小数据集,每个小数据集分配给一个线程进行处理。
2. 使用线程池:线程池可以管理线程的数量和生命周期,避免线程数量过多或过少的问题。
3. 使用异步编程:异步编程可以将耗时的操作放在后台线程中执行,避免阻塞主线程。
4. 使用分布式处理:将大数据集分散到多台计算机上进行处理,可以提高计算速度和效率。
5. 优化算法:通过改进算法,减少计算量,从而减少线程的数量需求。
用java和sql sever写一个学生信息管理系统
以下是一个简单的学生信息管理系统的Java代码和SQL Server数据库:
Java代码:
```java
import java.sql.*;
public class StudentManagementSystem {
// Establishing a database connection
private static Connection getConnection() {
Connection con = null;
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
String url = "jdbc:sqlserver://localhost:1433;databaseName=student_db";
String username = "sa";
String password = "password";
con = DriverManager.getConnection(url, username, password);
} catch (Exception e) {
e.printStackTrace();
}
return con;
}
// Adding a new student to the database
public static void addStudent(String name, int age, String gender, String address, String phone) {
try {
Connection con = getConnection();
PreparedStatement ps = con.prepareStatement("insert into students(name, age, gender, address, phone) values(?,?,?,?,?)");
ps.setString(1, name);
ps.setInt(2, age);
ps.setString(3, gender);
ps.setString(4, address);
ps.setString(5, phone);
ps.executeUpdate();
System.out.println("Student added successfully!");
con.close();
} catch (Exception e) {
e.printStackTrace();
}
}
// Updating an existing student in the database
public static void updateStudent(int id, String name, int age, String gender, String address, String phone) {
try {
Connection con = getConnection();
PreparedStatement ps = con.prepareStatement("update students set name=?, age=?, gender=?, address=?, phone=? where id=?");
ps.setString(1, name);
ps.setInt(2, age);
ps.setString(3, gender);
ps.setString(4, address);
ps.setString(5, phone);
ps.setInt(6, id);
ps.executeUpdate();
System.out.println("Student updated successfully!");
con.close();
} catch (Exception e) {
e.printStackTrace();
}
}
// Deleting a student from the database
public static void deleteStudent(int id) {
try {
Connection con = getConnection();
PreparedStatement ps = con.prepareStatement("delete from students where id=?");
ps.setInt(1, id);
ps.executeUpdate();
System.out.println("Student deleted successfully!");
con.close();
} catch (Exception e) {
e.printStackTrace();
}
}
// Displaying all students in the database
public static void viewStudents() {
try {
Connection con = getConnection();
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select * from students");
while (rs.next()) {
System.out.println("ID: " + rs.getInt("id"));
System.out.println("Name: " + rs.getString("name"));
System.out.println("Age: " + rs.getInt("age"));
System.out.println("Gender: " + rs.getString("gender"));
System.out.println("Address: " + rs.getString("address"));
System.out.println("Phone: " + rs.getString("phone"));
System.out.println();
}
con.close();
} catch (Exception e) {
e.printStackTrace();
}
}
// Main method to test the program
public static void main(String[] args) {
addStudent("John Doe", 20, "Male", "123 Main St", "555-1234");
addStudent("Jane Smith", 21, "Female", "456 Oak Ave", "555-5678");
viewStudents();
updateStudent(1, "Johnny Doe", 21, "Male", "123 Main St", "555-1234");
deleteStudent(2);
viewStudents();
}
}
```
SQL Server数据库:
```sql
create database student_db;
use student_db;
create table students(
id int primary key identity(1,1),
name varchar(50) not null,
age int not null,
gender varchar(10) not null,
address varchar(100) not null,
phone varchar(20) not null
);
```
注意:这只是一个简单的示例程序,实际的学生信息管理系统需要更多的功能和完善的错误处理。同时,本程序的数据库连接信息(url、username、password)应该根据你的实际情况进行修改。