java与数据库连接并对表进行添加、修改、删除操作

mysql版本 8.0.29 jar包与之对应

往mysql中account表中添加一个记录
不抛异常写法：

package cn.itcast.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;




public class jdbcDemo02 {
    public static void main(String[] args) {
        Statement stmt = null;
        Connection conn = null;
        try {
            //1注册驱动
            //8.0版本与5.7写法不一样 这里是8.0版本
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2定义sql
            String sql = "insert into account values(null,'王五',1000)";
            //3获取Connection对象
            //8.0版本！！！
            conn = DriverManager.getConnection("jdbc:mysql:///db3?serverTimezone=UTC", "root", "root");
            //4获取执行sql的对象 Statement
            stmt = conn.createStatement();
            //5执行sql
            int count = stmt.executeUpdate(sql);//影响的行数
            //6处理结果
            System.out.println(count);

            if(count>0){
                System.out.println("添加成功！");
            }else {
                System.out.println("添加失败！");
            }



        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            //释放资源
            //避免空指针异常
            if(stmt!=null){
                try {
                    stmt.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }

            if(conn!=null){
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }


    }
}

修改表中记录

package cn.itcast.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;




public class jdbcDemo03 {
    public static void main(String[] args) {
        Statement stmt = null;
        Connection conn = null;
        //1加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2定义sql
            String sql = "update account set balance =1000 where id =7";
            //3获取Connection对象
            conn = DriverManager.getConnection("jdbc:mysql:///db3?serverTimezone=UTC", "root", "root");
            //4获取执行sql的对象 Statement
            stmt = conn.createStatement();
            //5执行sql
            int count = stmt.executeUpdate(sql);//影响的行数
            //6处理结果
            System.out.println(count);

            if(count>0){
                System.out.println("修改成功！");
            }else {
                System.out.println("修改失败！");
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            //释放资源
            //避免空指针异常
            if(stmt!=null){
                try {
                    stmt.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }

            if(conn!=null){
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}

删除表中记录

package cn.itcast.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;




public class jdbcDemo04 {
    public static void main(String[] args) {
        Statement stmt = null;
        Connection conn = null;
        //1加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2定义sql
            String sql = "DELETE FROM ACCOUNT WHERe id = 8";
            //3获取Connection对象
            conn = DriverManager.getConnection("jdbc:mysql:///db3?serverTimezone=UTC", "root", "root");
            //4获取执行sql的对象 Statement
            stmt = conn.createStatement();
            //5执行sql
            int count = stmt.executeUpdate(sql);//影响的行数
            //6处理结果
            System.out.println(count);

            if(count>0){
                System.out.println("删除成功！");
            }else {
                System.out.println("删除失败！");
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            //释放资源
            //避免空指针异常
            if(stmt!=null){
                try {
                    stmt.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }

            if(conn!=null){
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}