【Java1029】使用JDBC增删改表格数据

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


public class demo1 {
    public static void  main(String[] args){
        Statement stmt = null;
        Connection conn = null;
        try {
            //注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            //定义sql
            String sql="insert into account values(null,'王五'，3000)";
            //获取Connection对象
            conn = DriverManager.getConnection("jdbc:mysql:///db3","root","admin");
            //获取执行sql的对象，Statement
            stmt = conn.createStatement();
            //执行sql
            int count = stmt.executeUpdate(sql);  //count为影响的行数
            System.out.println(count);
            if(count>0){
                System.out.println("添加成功");
            }else {
                System.out.println("添加失败");
            }
        } catch (SQLException throwables) {
                throwables.printStackTrace();
            
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }finally {
            //stmt.close();
            //释放资源
            //避免空指针异常
            if(stmt!=null){
                try {
                    stmt.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }

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

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

import static java.lang.Class.forName;



public class demo2 {
    public static void main(String[] args) {
        Connection conn = null;
        Statement stmt =null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql///db3", "root", "admin");
            String sql = "Update account set balance = 1500 where id =3";
            stmt = conn.createStatement();
            int count = stmt.executeUpdate(sql);
            System.out.println(count);
            if (count > 0) {
                System.out.println("更新成功");                
            }else{
                System.out.println("修改失败");
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            if(stmt!=null){
                try {
                    stmt.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
            if(conn!=null){
                try {
                    conn.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
        }
    }
}

import java.sql.*;

import static java.lang.Class.forName;

public class demo {
    public static void main(String[] args) {
        Connection conn = null;
        Statement stmt = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("mysql:///db3", "root", "admin");
            String sql = "delete from account where id=3";
            stmt = conn.createStatement();
            int count = stmt.executeUpdate(sql);
            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 throwables) {
            throwables.printStackTrace();
        }finally {
            if(conn!=null){
                try {
                    conn.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
            if(stmt != null){
                try {
                    stmt.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
        }
    }
}