sql在javaweb开发写法

首先你需要会sql语言，如果你对sql不太会可以看这篇帖子（https://blog.csdn.net/baidu_38978508/article/details/88901870）
为了让大家更好的理解在javweb开发的sql的增删查改，下面的例子都是以整个函数进行的。
1、增（insert）
重点！！！！！！！！！！！！！！！！！！！！！！
sql语言，也就是要即将进行执行的语言。

String sql = "insert  into room(name,email,phone,sex,money,price,type,time,content) values(?,?,?,?,?,?,?,?,?)";//sql语言

给占位符穿参数

stm = conn.prepareStatement(sql);//预处理的对象
			stm.setString(1, name);//这里进行传参数，非常重要
			stm.setString(2, email);
			stm.setString(3, phone);
			stm.setString(4, sex);
			stm.setInt(5, money);
			stm.setString(6, price);
			stm.setString(7, type);
			stm.setString(8, time);
			stm.setString(9, content);
			rs = stm.executeUpdate();//动态的执行insert updata delete的语句

整个函数

public void addRoom(String name,int money, String email, String phone, String type, String sex, String price, String time,
			String content) {
		// TODO Auto-generated method stub
		Connection conn = DBUtil.getConnectDb();
		String sql = "insert  into room(name,email,phone,sex,money,price,type,time,content) values(?,?,?,?,?,?,?,?,?)";//sql语言
		int rs = 0;
		PreparedStatement stm = null;
		try {
			stm = conn.prepareStatement(sql);//预处理的对象
			stm.setString(1, name);//这里进行传参数，非常重要
			stm.setString(2, email);
			stm.setString(3, phone);
			stm.setString(4, sex);
			stm.setInt(5, money);
			stm.setString(6, price);
			stm.setString(7, type);
			stm.setString(8, time);
			stm.setString(9, content);
			rs = stm.executeUpdate();//动态的执行insert updata delete的语句
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

2、查（select）
（1）没有参数的查询

public ArrayList<RoomBean> getRoomList() {
		// TODO Auto-generated method stub
		ArrayList<RoomBean> tag_Array = new ArrayList<RoomBean>();
		Connection conn = DBUtil.getConnectDb();
		String sql = "select * from room";//从room表中拿到数据
		PreparedStatement stm = null;
		ResultSet rs = null;
		try {
			stm = conn.prepareStatement(sql);
			rs = stm.executeQuery();
			while(rs.next()){//通过游标提取数据，进行循环
				RoomBean tag = new RoomBean();
				tag.setId(rs.getInt("id"));
				tag.setName(rs.getString("name"));
				tag.setEmail(rs.getString("email"));
				tag.setPhone(rs.getString("phone"));
				tag.setSex(rs.getString("sex"));
				tag.setMoney(rs.getInt("money"));
				tag.setPrice(rs.getString("price"));
				tag.setType(rs.getString("type"));
				tag.setTime(rs.getString("time"));
				tag.setContent(rs.getString("content"));
				tag_Array.add(tag);
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			DBUtil.CloseDB(rs, stm, conn);
		}
		return tag_Array;
	}

（2）传参数进行查询

public int  getRoom(int id) {
		// TODO Auto-generated method stub
		int money = 0;
		Connection conn = DBUtil.getConnectDb();
		String sql = "select * from room where id="+id;
		PreparedStatement stm = null;
		ResultSet rs = null;//相当于临时表
		try {
			stm = conn.prepareStatement(sql);//预处理对象
			rs = stm.executeQuery();//获取结果集
			//从当前游标开始到下一行next
			if(rs.next()){
				money = rs.getInt("money");
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			DBUtil.CloseDB(rs, stm, conn);
		}
		return money;
	}

3、更新（update）

	public void updateRoom(int id, int price) {
		// TODO Auto-generated method stub
		Connection conn = DBUtil.getConnectDb();
		String sql = "update room set money=? where id=?";//sql
		PreparedStatement stm = null;
		int money = this.getRoom(id);
		money = money - price;
		try {
			stm = conn.prepareStatement(sql);
			stm.setInt(1, money);//传参数同样很重要
			stm.setInt(2, id);
		
			stm.executeUpdate();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

4、删除（delete）

public void deleteRoom(int id) {
		// TODO Auto-generated method stub
		Connection conn = DBUtil.getConnectDb();
		String sql = "delete from room where id=?";
		PreparedStatement stm = null;
		try {
			stm = conn.prepareStatement(sql);
			stm.setInt(1, id);
			stm.executeUpdate();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

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