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Merged
hcsp-bot merged 1 commit into from
Jun 1, 2020
Merged

change to another file #133

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99 changes: 88 additions & 11 deletions src/main/java/com/github/hcsp/sql/Sql.java
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Original file line number Diff line number Diff line change
@@ -1,10 +1,14 @@

package com.github.hcsp.sql;

import java.io.File;
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class Sql {
Expand Down Expand Up @@ -68,7 +72,7 @@ public String toString() {
}
}

/**
/*
* 题目1：
* 查询有多少所有用户曾经买过指定的商品
*
Expand All @@ -82,14 +86,21 @@ public String toString() {
// | 2 |
// +-----+
public static int countUsersWhoHaveBoughtGoods(Connection databaseConnection, Integer goodsId) throws SQLException {
return 0;
PreparedStatement statement = databaseConnection.prepareStatement("select count (distinct USER_ID) from `ORDER` where GOODS_ID = ?");
statement.setInt(1, goodsId);

ResultSet resultSet = statement.executeQuery();
while (resultSet.next()) {
return resultSet.getInt(1);
}
return -1;
}

/**
/*
* 题目2：
* 分页查询所有用户，按照ID倒序排列
*
* @param pageNum 第几页，从1开始
* @param pageNum 第几页，从1开始
* @param pageSize 每页有多少个元素
* @return 指定页中的用户
*/
Expand All @@ -100,7 +111,23 @@ public static int countUsersWhoHaveBoughtGoods(Connection databaseConnection, In
// | 1 | zhangsan | tel1 | beijing |
// +----+----------+------+----------+
public static List<User> getUsersByPageOrderedByIdDesc(Connection databaseConnection, int pageNum, int pageSize) throws SQLException {
return null;
PreparedStatement statement = databaseConnection.prepareStatement("select * from user order by id desc limit ?,? ");

statement.setInt(1, pageSize);
statement.setInt(2, (pageNum - 1) * pageSize);

ResultSet resultSet = statement.executeQuery();

List<User> list = new ArrayList<>();
while (resultSet.next()) {
User user = new User();
user.id = resultSet.getInt(1);
user.name = resultSet.getNString(2);
user.tel = resultSet.getNString(3);
user.address = resultSet.getString(4);
list.add(user);
}
return list;
}

// 商品及其营收
Expand All @@ -115,7 +142,7 @@ public String toString() {
}
}

/**
/*
* 题目3：
* 查询所有的商品及其销售额，按照销售额从大到小排序
*/
Expand All @@ -132,7 +159,22 @@ public String toString() {
// | 3 | goods3 | 20 |
// +----+--------+------+
public static List<GoodsAndGmv> getGoodsAndGmv(Connection databaseConnection) throws SQLException {
return null;
PreparedStatement statement = databaseConnection.prepareStatement("select `ORDER`.GOODS_ID,GOODS.NAME, sum(`ORDER`.GOODS_NUM*`ORDER`.GOODS_PRICE) as total from `ORDER`\n"
+ "join GOODS on `ORDER`.GOODS_ID = GOODS.ID\n"
+ "group by `ORDER`.GOODS_ID \n"
+ "order by total desc ");


ResultSet resultSet = statement.executeQuery();
List<GoodsAndGmv> list = new ArrayList<>();
while (resultSet.next()) {
GoodsAndGmv goodsAndGmv = new GoodsAndGmv();
goodsAndGmv.goodsId = resultSet.getInt(1);
goodsAndGmv.goodsName = resultSet.getNString(2);
goodsAndGmv.gmv = resultSet.getBigDecimal(3);
list.add(goodsAndGmv);
}
return list;
}


Expand All @@ -149,7 +191,7 @@ public String toString() {
}
}

/**
/*
* 题目4：
* 查询订单信息，只查询用户名、商品名齐全的订单，即INNER JOIN方式
*/
Expand All @@ -170,10 +212,27 @@ public String toString() {
// | 6 | zhangsan | goods3 | 20 |
// +----------+-----------+------------+-------------+
public static List<Order> getInnerJoinOrders(Connection databaseConnection) throws SQLException {
return null;
PreparedStatement statement = databaseConnection.prepareStatement("select `ORDER`.ID, USER.NAME , GOODS.NAME, sum(GOODS_PRICE*GOODS_NUM) as TOTAL_PRICE from `ORDER` \n"
+ " join GOODS\n"
+ " on `ORDER`.GOODS_ID = GOODS.ID\n"
+ " join USER\n"
+ " on `ORDER`.USER_ID = USER.ID\n"
+ "group by `ORDER`.ID\n");

ResultSet resultSet = statement.executeQuery();
List<Order> list = new ArrayList<>();
while (resultSet.next()) {
Order order = new Order();
order.id = resultSet.getInt(1);
order.userName = resultSet.getNString(2);
order.goodsName = resultSet.getNString(3);
order.totalPrice = resultSet.getBigDecimal(4);
list.add(order);
}
return list;
}

/**
/*
* 题目5：
* 查询所有订单信息，哪怕它的用户名、商品名缺失，即LEFT JOIN方式
*/
Expand All @@ -198,7 +257,25 @@ public static List<Order> getInnerJoinOrders(Connection databaseConnection) thro
// | 8 | NULL | NULL | 60 |
// +----------+-----------+------------+-------------+
public static List<Order> getLeftJoinOrders(Connection databaseConnection) throws SQLException {
return null;
try (PreparedStatement statement = databaseConnection.prepareStatement("select `ORDER`.id, user.NAME as user_name, GOODS.NAME as goods_name, `ORDER`.GOODS_NUM * GOODS_PRICE\n"
+ "from \"ORDER\"\n"
+ " left join GOODS\n"
+ " on \"ORDER\".GOODS_ID= GOODS.id\n"
+ " left join USER\n"
+ " on \"ORDER\".USER_ID = USER.ID\n")) {
ResultSet resultSet = statement.executeQuery();

List<Order> orders = new ArrayList<>();
while (resultSet.next()) {

@hcsp-bot hcsp-bot Jun 3, 2020

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你看这个方法是不是和getInnerJoinOrders有大量的代码重复？考虑过抽取一个公用方法出来么？

Order order = new Order();
order.id = resultSet.getInt(1);
order.userName = resultSet.getNString(2);
order.goodsName = resultSet.getNString(3);
order.totalPrice = resultSet.getBigDecimal(4);
orders.add(order);
}
return orders;
}
}

// 注意，运行这个方法之前，请先运行mvn initialize把测试数据灌入数据库
Expand Down