MySQL 实现增删改查

摘要:

数据库可以帮助我们对数据进行持久化存储，所以我们需要学会如何去使用数据库，使用JAVA对数据库进行增删改查操作。

测试数据库:

person:

数据库操作代码:

package com.sql;

import java.sql.*;

public class DataBase {
    Connection conn = null;
    Statement st = null;

    public void Connect() throws
            SQLException, java.lang.ClassNotFoundException {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/test";
            String user = "root";
            String password = "123456";
            conn = DriverManager.getConnection(url, user, password);
            System.out.println("链接数据库成功！");
        } catch (Exception e) {
            System.out.println("链接数据库失败！");
            System.out.println(e.getMessage());

        }
    }

    public void addOnePerson() {
        try {
            st = conn.createStatement();
            st.executeUpdate("insert into person values (5,'xiaoming','girl')");
            System.out.println(" addOnePerson()添加信息成功！");
        } catch (SQLException e) {
            System.out.println("添加信息失败！");
            System.out.println(e.getMessage());

        }
    }

    public void queryPerson() {
        try {
            st = conn.createStatement();
            String StrSQL = "select * from person";
            ResultSet rs = st.executeQuery(StrSQL);
            System.out.println("person表的数据如下：");
            System.out.println("----------------！");
            System.out.println("--编号" + " --姓名" + "--性别");

            System.out.println("-------------------");
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                String sex = rs.getString("sex");

                System.out.println("--" + id + " --" + name + "--" + sex);
            }
        } catch (SQLException e) {
            System.out.println("加载失败！");
            System.out.println(e.getMessage());
        }
    }

    public void delOnePerson() {
        try {
            st = conn.createStatement();
            String StrSQL = "delete from person where id = 5";
            Boolean flag = st.execute(StrSQL);


            System.out.println("删除成功！");


        } catch (SQLException e) {
            System.out.println("加载失败！");
            System.out.println(e.getMessage());
        }
    }

    public void addPerson(int id, String name, String sex) {
        try {
            String sql = "insert into person(id,name,sex) values (?,? ,?)";
            PreparedStatement pst = conn.prepareStatement(sql);
            pst.setInt(1, id);
            pst.setString(2, name);
            pst.setString(3, sex);
            pst.executeUpdate();
            System.out.println("addPerson()添加信息成功！");
        } catch (SQLException e) {
            System.out.println("添加信息失败！");
            System.out.println(e.getMessage());

        }
    }

    public void delPerson(int id) {
        try {
            st = conn.createStatement();
            String StrSQL = "delete from person where id =" + id;
            Boolean flag = st.execute(StrSQL);


            System.out.println("删除" + id + "一行成功！");


        } catch (SQLException e) {
            System.out.println("加载失败！");
            System.out.println(e.getMessage());
        }
    }

    public void close_connection() {
        try {
            st.close();
            conn.close();
            System.out.println("数据库关闭成功！");
        } catch (Exception e) {
            System.out.println("数据库失败！");
            System.out.println(e.getMessage());
        }
    }
}

主程序测试:

package com.sql;

import java.sql.SQLException;

public class MainMySQL {

    /**
     * @param args
     */
    public static void main(String[] args)throws SQLException,java.lang.ClassNotFoundException{
        System.out.println("使用MySQL实例");
        DataBase db=new DataBase();
        db.Connect();
        db.addOnePerson();
        db.addPerson(1,"Alan","boy");
        db.queryPerson();
        db.delOnePerson();
        db.delPerson(1);
        db.close_connection();

    }
}

数据库操作是一个非常复杂的过程，其中牵扯许多数学知识如笛卡尔积等，不光光是简单的增删改查，可以关注后续可能会更新数据库各种优化操作，减少时间复杂度实验。