Java-mysql-000-连接、插入、查询、修改、删除

Java-mysql-000-连接、插入、查询、修改、删除-2020-6-25

一、connect.java

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
 
public class connect {
 
    public static void main(String[] args) {
        //声明Connection对象
        Connection con;
        //驱动程序名
        String driver = "com.mysql.cj.jdbc.Driver";
        //URL指向要访问的数据库名mysql（此处的test是你所javatest的那个database）
        String url = "jdbc:mysql://localhost:3306/javatest?useSSL=false&serverTimezone=UTC";
        //MySQL配置时的用户名
        String user = "root";
        //MySQL配置时的密码
        String password = "123456789";
        //遍历查询结果集
        try {
            //加载驱动程序
            Class.forName(driver);
            //1.getConnection()方法，连接MySQL数据库！！
            con = DriverManager.getConnection(url,user,password);
            if(!con.isClosed())
                System.out.println("Succeeded connecting to the Database!");
            //2.创建statement类对象，用来执行SQL语句！！
            Statement statement = con.createStatement();
            //要执行的SQL语句
            String sql = "select * from student";
            //3.ResultSet类，用来存放获取的结果集！！
            ResultSet rs = statement.executeQuery(sql);
            System.out.println("执行结果如下所示:");  
            System.out.println("-----------------");  
            System.out.println("姓名" + "\t" + "年龄"+ "\t" + "职位");  
            System.out.println("-----------------");  
             
            String name = null;
            String position = null;
            int age=0;
            while(rs.next()){
                //获取name这列数据
            	 name = rs.getString("name");
                //获取age这列数据
                age=rs.getInt("age");
                //获取position这列数据               
                position = rs.getString("position");
                //输出结果
                System.out.println(name + "\t" + age + "\t" + position);
            }
            rs.close();
            con.close();
        } catch(ClassNotFoundException e) {   
            //数据库驱动类异常处理
            System.out.println("Sorry,can`t find the Driver!");   
            e.printStackTrace();   
            } catch(SQLException e) {
            //数据库连接失败异常处理
            e.printStackTrace();  
            }catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }finally{
            System.out.println("数据库数据成功获取！！");
        }
    }
}

二、insert.java

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

public class insert {
    public static void main(String[] args) {
        try {
             // 加载数据库驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            // 声明数据库view的URL
            String url = "jdbc:mysql://localhost:3306/javatest?useSSL=false&serverTimezone=UTC";
            // 数据库用户名
            String user = "root"; 
            // 数据库密码
            String password = "123456789"; 
            // 建立数据库连接，获得连接对象conn
            Connection con = DriverManager.getConnection(url, user, password);
            String sql = "insert into student (name,age,position) values(?,?,?)"; // 生成一条sql语句
            // 创建一个Statment对象
            PreparedStatement ps = con.prepareStatement(sql);
            // 为sql语句中第一个问号赋值
            ps.setString(1, "李四");
            // 为sql语句中第二个问号赋值
            ps.setInt(2, 123);
            // 为sql语句中第三个问号赋值
            ps.setString(3, "插入");
            // 为sql语句中第四个问号赋值
            // 执行sql语句
            ps.executeUpdate();
            // 关闭数据库连接对象
            con.close();
            System.out.println("数据变化");
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

三、delete.java

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

public class delete {
	  public static void main(String[] args) {
	        try {
	             // 加载数据库驱动
	            Class.forName("com.mysql.cj.jdbc.Driver");
	            // 声明数据库view的URL
	            String url = "jdbc:mysql://localhost:3306/javatest?useSSL=false&serverTimezone=UTC";
	            // 数据库用户名
	            String user = "root"; 
	            // 数据库密码
	            String password = "123456789"; 
	            // 建立数据库连接，获得连接对象conn
	            Connection con = DriverManager.getConnection(url, user, password);
	            String sql = "delete from student where age = ?";
	            PreparedStatement stmt = con.prepareStatement(sql);
	            stmt.setInt(1, 123);
	            int result =stmt.executeUpdate();// 返回值代表收到影响的行数
	            if(result>0) {
	                System.out.println("删除成功");
	            }else {
	                System.out.println("删除失败");
	            }
	            con.close();
	            System.out.println("数据变化");
	        } catch (ClassNotFoundException e) {
	            // TODO Auto-generated catch block
	            e.printStackTrace();
	        } catch (SQLException e) {
	            // TODO Auto-generated catch block
	            e.printStackTrace();
	        }
	    }
}

四、update.java

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

public class update {
	public static void main(String[] args) {
        try {
             // 加载数据库驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            // 声明数据库view的URL
            String url = "jdbc:mysql://localhost:3306/javatest?useSSL=false&serverTimezone=UTC";
            // 数据库用户名
            String user = "root"; 
            // 数据库密码
            String password = "123456789"; 
            // 建立数据库连接，获得连接对象conn
            Connection con = DriverManager.getConnection(url, user, password);
            String sql = "update student set name = ? where age = ?";
            PreparedStatement stmt = con.prepareStatement(sql);
            stmt.setString(1, "小云");
            stmt.setInt(2, 12);
            int result =stmt.executeUpdate();// 返回值代表收到影响的行数
            if(result>0) {
                System.out.println("修改成功");
            }else {
                System.out.println("修改失败");
            }
            con.close();
            System.out.println("数据变化");
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}