1. Addition, deletion and modification of JDBC single table records
Known : create a table student, and insert several records into the table,
create table student(
id int PRIMARY KEY auto_increment,
name varchar(20) not null,
schoolin date not null,
score float not null);
insert into student values(null,'Li Li','2015-09-01',86);
insert into student values(null,'Wang Wu','2016-09-01',99);
insert into student values(null,'Zhang San','2014-09-01',88);
Requirements: Use JAVA program to achieve the following functions:
1. Add records to the table and display all records (data specified by yourself);
2. Delete the record with id=1 from the table and display all records;
3. Modify the records in the table: query condition id=2, modify the name to: Shandong University of Technology, and display all records after modification;
4. Query the record with id=3 in the table and display it;
1. Add records to the table and display all records (data specified by yourself)
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class Main {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
// 1 加载驱动
Class.forName("com.mysql.jdbc.Driver");
// 2 获得数据库的连接
Connection con =
DriverManager.getConnection
("jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf-8", "root", "");
//System.out.println(con);
// insert
String insertSQL="insert into student values(null,?,?)";
PreparedStatement pst1 = con.prepareStatement(insertSQL);
pst1.setString(1,"李四");
pst1.setInt(2, 25);
int result=pst1.executeUpdate();
if(result==1)
{
System.out.println("插入记录成功！");
}
//查询
ResultSet rs = pst.executeQuery();
while(rs.next())
{
int id=rs.getInt(1);
String name=rs.getString(2);
int age=rs.getInt(3);
System.out.println(id+"--"+name+"--"+age);
}
//7 关闭资源，关闭连接
pst3.close();
rs.close();
pst.close();
con.close();
}
}2. Delete the record with id=1 from the table and display all records;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class Main {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
// 1 加载驱动
Class.forName("com.mysql.jdbc.Driver");
// 2 获得数据库的连接
Connection con =
DriverManager.getConnection
("jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf-8", "root", "");
//System.out.println(con);
// delete
String deleteSQL="delete from student where id=?";
PreparedStatement pst2 = con.prepareStatement(deleteSQL);
pst2.setInt(1, 1);
int result1=pst2.executeUpdate();
if(result1==1)
{
System.out.println("删除记录成功！");
}
//6 查询
ResultSet rs = pst.executeQuery();
while(rs.next())
{
int id=rs.getInt(1);
String name=rs.getString(2);
int age=rs.getInt(3);
System.out.println(id+"--"+name+"--"+age);
}
//7 关闭资源，关闭连接
pst3.close();
rs.close();
pst.close();
con.close();
}
}3. Modify the records in the table: query condition id=2, modify the name to: Shandong University of Technology, and display all records after modification;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class Main {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
// 1 加载驱动
Class.forName("com.mysql.jdbc.Driver");
// 2 获得数据库的连接
Connection con =
DriverManager.getConnection
("jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf-8", "root", "");
//System.out.println(con);
//5 update
String updateSQL="update student set name=? where id=?";
PreparedStatement pst3 = con.prepareStatement(updateSQL);
pst3.setString(1,"山东理工");
pst3.setInt(2, 2);//id为2.where后面是条件
int result=pst3.executeUpdate();
if(result==1)
{
System.out.println("修改记录成功！");
}
String sql="select * from student";
PreparedStatement pst = con.prepareStatement(sql);
//6 查询
ResultSet rs = pst.executeQuery();
while(rs.next())
{
int id=rs.getInt(1);
String name=rs.getString(2);
int age=rs.getInt(3);
System.out.println(id+"--"+name+"--"+age);
}
//7 关闭资源，关闭连接
pst3.close();
rs.close();
pst.close();
con.close();
}
}4. Query the record with id=3 in the table and display it;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class Main {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
// 1 加载驱动
Class.forName("com.mysql.jdbc.Driver");
// 2 获得数据库的连接
Connection con =
DriverManager.getConnection
("jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf-8", "root", "");
//System.out.println(con);
//根据主键（id）来查询记录
String sql = "select * from student where id = ?";
pst = con.prepareStatement(sql);
ResultSet rs = pst.executeQuery();
pst.setInt(1, 3);//id为3
//查到或者没查到
Student stu = null;
if(rs.next()){
stu = new Student(rs.getInt(1), rs.getString(2), rs.getInt(3));
}
//7 关闭资源，关闭连接
pst3.close();
rs.close();
pst.close();
con.close();
}
}Second, JDBC object-oriented way to achieve database CRUD operations. (30 points)
Known: Create a table student and insert several records into the table.
create table student(
id int PRIMARY KEY auto_increment,
name varchar(20) not null,
schoolin date not null,
score float not null);
insert into student values(null,'Li Li','2015-09-01',86);
insert into student values(null,'Wang Wu','2016-09-01',99);
insert into student values(null,'Zhang San','2014-09-01',88);
Basic requirements: Encapsulate table operations into classes, and encapsulate functions into class methods.
Functional requirements:
(1) Add records to the table and display all records (data specified by yourself);
(2) Delete the record with id=1 from the table and display all records;
(3) Modify the records in the table: query condition id=2, modify the name to: Shandong University of Technology, and display all records after modification;
(4) Query the record with id=3 in the table and display it.
Student class: Student.java
public class Student {
private int id;
private String name;
private int age;
public Student(int id, String name, int age) {
super();
this.id = id;
this.name = name;
this.age = age;
}
public Student() {
super();
}
@Override
public String toString() {
return "Student [id=" + id + ", name=" + name + ", age=" + age + "]";
}
//因为三个属性是私有的，所有可以通过get和set方法取值，赋值
//变量设置成私有的，方法设置成公开的！-----类的封装
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
1. Add records to the table and display all records (data specified by yourself);
Student table operation class: StudentDao.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
public class StudentDao {
Connection con;
PreparedStatement pst;
public Connection getConn() throws SQLException, ClassNotFoundException{
//1加载驱动
Class.forName("com.mysql.jdbc.Driver");
//2获得数据库的连接
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf-8", "root", "");//协议+数据库+端口号+数据库名---------用户名--------密码为空
return con;
}
//增
public int addStudent(Student student) throws ClassNotFoundException, SQLException{
con = getConn();
String insertSQL = "insert into student values(null, ?, ?)";//准备sql语句
pst = con.prepareStatement(insertSQL);//准备sql语句的对象
//给？赋值
pst.setString(1, student.getName());
pst.setInt(2, student.getAge());
int result = pst.executeUpdate();
pst.close();
con.close();
return result;
}
//查询所有记录
public List<Student> queryAll() throws ClassNotFoundException, SQLException{
con = getConn();
String sql = "select * from student";
pst = con.prepareStatement(sql);
rs = pst.executeQuery();
List<Student> list = new ArrayList<Student>();//创建链表容器来存放数据
while(rs.next()) {
/*int id = rs.getInt(1);//列是从1开始的
String name = rs.getString(2);
int age = rs.getInt(3);
Student stu = new Student(id, name, age);*/
// Student stu = new Student(rs.getInt(1), rs.getString(2), rs.getInt(3));
Student stu = new Student();
stu.setId(rs.getInt(1));
stu.setName(rs.getString(2));
stu.setAge(rs.getInt(3));
list.add(stu);
}
return list;
}Test class: Main.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
public class Main {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
StudentDao dao=new StudentDao();
Student stu1=new Student(1,"系统",22);
int result = dao.addStudent(stu1);
if(result==1)
{
System.out.println("插入记录成功！");
}
//显示所有记录
List<Student> stuList=dao.queryAll();
for(Student stu:stuList)
{
System.out.println(stu);
}
System.out.println("=======");
}
}2. Delete the record with id=1 from the table and display all records;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
public class StudentDao {
Connection con;
PreparedStatement pst;
public Connection getConn() throws SQLException, ClassNotFoundException{
//1加载驱动
Class.forName("com.mysql.jdbc.Driver");
//2获得数据库的连接
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf-8", "root", "");//协议+数据库+端口号+数据库名---------用户名--------密码为空
return con;
}
//删
public int deleteStudent(int id) throws ClassNotFoundException, SQLException{
con = getConn();
String sql = "delete from student where id=?";//准备sql语句
pst = con.prepareStatement(sql);//准备sql语句的对象
//给？赋值
pst.setInt(1, 1);//删除的条件是id=1
int result = pst.executeUpdate();
pst.close();
con.close();
return result;
}
//查询所有记录
public List<Student> queryAll() throws ClassNotFoundException, SQLException{
con = getConn();
String sql = "select * from student";
pst = con.prepareStatement(sql);
rs = pst.executeQuery();
List<Student> list = new ArrayList<Student>();//创建链表容器来存放数据
while(rs.next()) {
/*int id = rs.getInt(1);//列是从1开始的
String name = rs.getString(2);
int age = rs.getInt(3);
Student stu = new Student(id, name, age);*/
// Student stu = new Student(rs.getInt(1), rs.getString(2), rs.getInt(3));
Student stu = new Student();
stu.setId(rs.getInt(1));
stu.setName(rs.getString(2));
stu.setAge(rs.getInt(3));
list.add(stu);
}
return list;
}
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
public class Main {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
StudentDao dao=new StudentDao();
int result2 = dao.delStudent(1);
if(result2==1)
{
System.out.println("删除记录成功！");
}
List<Student> stuList=dao.queryAll();
for(Student stu:stuList)
{
System.out.println(stu);
}
System.out.println("=======");
}
}3. Modify the records in the table: query condition id=2, modify the name to: Shandong University of Technology, and display all records after modification;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
public class StudentDao {
Connection con;
PreparedStatement pst;
public Connection getConn() throws SQLException, ClassNotFoundException{
//1加载驱动
Class.forName("com.mysql.jdbc.Driver");
//2获得数据库的连接
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf-8", "root", "");//协议+数据库+端口号+数据库名---------用户名--------密码为空
return con;
}
//改
public int updateStudent() throws ClassNotFoundException, SQLException{
con = getConn();
String sql = "update student set name = ? where id = ?";//准备sql语句
pst = con.prepareStatement(sql);//准备sql语句的对象
//给？赋值
pst.setString(1, "山东理工");
pst.setInt(2, 2);//修改id为2的name
int result = pst.executeUpdate();
pst.close();
con.close();
return result;
}
//查询所有记录
public List<Student> queryAll() throws ClassNotFoundException, SQLException{
con = getConn();
String sql = "select * from student";
pst = con.prepareStatement(sql);
rs = pst.executeQuery();
List<Student> list = new ArrayList<Student>();//创建链表容器来存放数据
while(rs.next()) {
/*int id = rs.getInt(1);//列是从1开始的
String name = rs.getString(2);
int age = rs.getInt(3);
Student stu = new Student(id, name, age);*/
// Student stu = new Student(rs.getInt(1), rs.getString(2), rs.getInt(3));
Student stu = new Student();
stu.setId(rs.getInt(1));
stu.setName(rs.getString(2));
stu.setAge(rs.getInt(3));
list.add(stu);
}
return list;
}
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
public class Main {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
StudentDao dao=new StudentDao();
int result3 = dao.updateStudent();
if(result3==1)
{
System.out.println("修改记录成功！");
}
List<Student> stuList=dao.queryAll();
for(Student stu:stuList)
{
System.out.println(stu);
}
System.out.println("=======");
}
}4. Query the record with id=3 in the table and display it.
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
public class StudentDao {
Connection con;
PreparedStatement pst;
public Connection getConn() throws SQLException, ClassNotFoundException{
//1加载驱动
Class.forName("com.mysql.jdbc.Driver");
//2获得数据库的连接
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf-8", "root", "");//协议+数据库+端口号+数据库名---------用户名--------密码为空
return con;
}
//根据主键查询记录
public Student queryById(int id) throws ClassNotFoundException, SQLException{
con = getConn();
String sql = "select * from student where id = ?";
pst = con.prepareStatement(sql);
ResultSet rs = pst.executeQuery();
pst.setInt(1, 3);//查询id为3的记录
//查到或者没查到
Student stu = null;
if(rs.next()){
stu = new Student(rs.getInt(1), rs.getString(2), rs.getInt(3));
}
return stu;
}import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
public class Main {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
StudentDao dao=new StudentDao();
List<Student> stuList=dao.queryAll();
for(Student stu:stuList)
{
System.out.println(stu);
}
System.out.println("=======");
}
}