package com.jdbcdemo;

import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class Jdbcdemo {
	private static Connection con; // 連線資料庫
	private static Driver dri; // 驅動
	private static Statement sta;
	private static ResultSet res; // 結果集

	public static Connection getconnection() {
		con = null;
		String url = "jdbc:mysql://localhost:3306/javademo"; // 資料庫的埠，及資料庫名稱
		String user = "root";
		String password = "hj1995HJ";
		try {
			Class.forName("com.mysql.jdbc.Driver");
			con = DriverManager.getConnection(url, user, password); // 連線資料庫
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return con;
	}

	public static void query() { // 查詢資料庫
		try {
			con = getconnection();
			String sql = "select * from user"; // sql語句
			sta = con.createStatement(); // 連線資料庫
			res = sta.executeQuery(sql); // 執行SQL語句返回結果集
			while (res.next()) {
				String name = res.getString("name");
				int age = res.getInt("age");
				int number = res.getInt("number");
				System.out.println("name : " + name + " " + "age : " + age + " number: " + number); // 查詢的內容打印出來
			}
			if (res != null) { // 關閉結果集
				res.close();
			}
			if (sta != null) { // 關閉資料庫連線
				sta.close();
			}
			if (con != null) { // 關閉連線
				con.close();
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void insert() { // 插入資料庫
		try {
			int a;
			con = getconnection();
			String sql = "insert into user (name,age,number) values ('hongjun',22,148101)";
			sta = con.createStatement();
			a = sta.executeUpdate(sql);
			System.out.println("改變的行數為 ： " + a);
			query();
			if (res != null) {
				res.close();
			}
			if (sta != null) {
				sta.close();
			}
			if (con != null) {
				con.close();
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void delete() { // 刪除資料庫
		try {
			int a;
			con = getconnection();
			String sql = "delete from user where name='hongjun'";
			sta = con.createStatement();
			a = sta.executeUpdate(sql);
			System.out.println("改變的行數為 ： " + a);
			query();
			if (res != null) {
				res.close();
			}
			if (sta != null) {
				sta.close();
			}
			if (con != null) {
				con.close();
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void changdata() { // 修改資料庫
		try {
			int a;
			con = getconnection();
			String sql = "update user set number=100 where name='hong'";
			sta = con.createStatement();
			a = sta.executeUpdate(sql);
			System.out.println("改變的行數為 ： " + a);
			query();
			if (res != null) {
				res.close();
			}
			if (sta != null) {
				sta.close();
			}
			if (con != null) {
				con.close();
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void prequery() { // 預編譯查詢資料庫
		con = getconnection();
		String sql = "select * from user";
		PreparedStatement pst;
		try {
			pst = con.prepareStatement(sql);
			res = pst.executeQuery();
			while (res.next()) {
				String name = res.getString("name");
				int age = res.getInt("age");
				int number = res.getInt("number");
				System.out.println("name : " + name + " " + "age : " + age + " number: " + number);
			}
			if (res != null) {
				res.close();
			}
			if (pst != null) {
				pst.close();
			}
			if (con != null) {
				con.close();
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void preinsert() { // 預編譯插入資料庫
		int a;
		con = getconnection();
		String sql = "insert into user (name,age,number) values ('hongjun',22,148101)";
		PreparedStatement pst;
		try {
			pst = con.prepareStatement(sql);
			a = pst.executeUpdate();
			System.out.println("改變的行數為 ： " + a);
			query();
			if (res != null) {
				res.close();
			}
			if (pst != null) {
				pst.close();
			}
			if (con != null) {
				con.close();
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void predelete() { // 預編譯刪除資料庫
		int a;
		con = getconnection();
		String sql = "delete from user where name='hongjun'";
		PreparedStatement pst;
		try {
			pst = con.prepareStatement(sql);
			a = pst.executeUpdate();
			System.out.println("改變的行數為 ： " + a);
			query();
			if (res != null) {
				res.close();
			}
			if (pst != null) {
				pst.close();
			}
			if (con != null) {
				con.close();
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void prechangdate() { // 預編譯刪除資料庫
		int a;
		con = getconnection();
		String sql = "update user set number=100 where name='hong'";
		PreparedStatement pst;
		try {
			pst = con.prepareStatement(sql);
			a = pst.executeUpdate();
			System.out.println("改變的行數為 ： " + a);
			query();
			if (res != null) {
				res.close();
			}
			if (pst != null) {
				pst.close();
			}
			if (con != null) {
				con.close();
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {
		query(); // 查詢資料庫
		insert(); // 插入資料庫
		delete(); // 刪除資料庫資料
		changdata(); // 修改資料
		prequery(); // 預編譯處理查詢
		preinsert(); // 預編譯插入查詢
		predelete();// 預編譯刪除查詢
		prechangdate(); // 預編譯處理
	}
}