Skip to content

select和jdbc的使用 #186

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
hahaen wants to merge 2 commits into
base: master
Choose a base branch
from
Open

select和jdbc的使用 #186

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
b8bd367
select和jdbc的使用
hahaen Sep 23, 2021
9f106aa
改
hahaen Sep 25, 2021
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
96 changes: 87 additions & 9 deletions src/main/java/com/github/hcsp/sql/Sql.java
View file
Open in desktop
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.sql.DriverManager;
import java.util.ArrayList;
import java.util.List;

public class Sql {
Expand Down Expand Up @@ -81,15 +85,24 @@ public String toString() {
// +-----+
// | 2 |
// +-----+
public static int countUsersWhoHaveBoughtGoods(Connection databaseConnection, Integer goodsId) throws SQLException {
return 0;
public static int countUsersWhoHaveBoughtGoods(Connection databaseConnection, Integer goodsId) throws SQLException, SQLException {
try (PreparedStatement statement = databaseConnection.prepareStatement("select count(*)\n"
+ "from \"ORDER\"\n"
+ "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 +113,24 @@ 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;
try (PreparedStatement statement = databaseConnection.prepareStatement("select *\n"
+ "from USER\n"
+ "order by id desc\n"
+ "limit ?,?\n")) {
statement.setInt(1, pageNum);
statement.setInt(2, 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.getString(2);
user.tel = resultSet.getString(3);
user.address = resultSet.getString(4);
list.add(user);
}
return list;
}
}

// 商品及其营收
Expand Down Expand Up @@ -132,10 +162,24 @@ public String toString() {
// | 3 | goods3 | 20 |
// +----+--------+------+
public static List<GoodsAndGmv> getGoodsAndGmv(Connection databaseConnection) throws SQLException {
return null;
try (PreparedStatement statement = databaseConnection.prepareStatement("select GOODS_ID,GOODS.NAME, sum(GOODS_NUM * GOODS_PRICE) as gmv\n"
+ "from \"ORDER\"\n"
+ "join GOODS on \"ORDER\".GOODS_ID = GOODS.ID\n"
+ "group by GOODS_ID\n"
+ "order by gmv 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.getString(2);
goodsAndGmv.gmv = resultSet.getBigDecimal(3);
list.add(goodsAndGmv);
}
return list;
}
}


// 订单详细信息
public static class Order {
Integer id; // 订单ID
Expand Down Expand Up @@ -170,7 +214,24 @@ public String toString() {
// | 6 | zhangsan | goods3 | 20 |
// +----------+-----------+------------+-------------+
public static List<Order> getInnerJoinOrders(Connection databaseConnection) throws SQLException {
return null;
try (PreparedStatement statement = databaseConnection.prepareStatement("select \"ORDER\".id,USER.NAME,GOODS.NAME,(GOODS_NUM * GOODS_PRICE) as totalPrice\n"
+ "from \"ORDER\"\n"
+ " inner join GOODS\n"
+ " on \"ORDER\".GOODS_ID = GOODS.ID\n"
+ " inner join USER\n"
+ " on \"ORDER\".USER_ID = USER.ID")) {
ResultSet resultSet = statement.executeQuery();
List<Order> list = new ArrayList<>();
while (resultSet.next()) {
Order order = new Order();
order.id = resultSet.getInt(1);
order.userName = resultSet.getString(2);
order.goodsName = resultSet.getString(3);
order.totalPrice = resultSet.getBigDecimal(4);
list.add(order);
}
return list;
}
}

/**
Expand Down Expand Up @@ -198,7 +259,24 @@ 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,GOODS.NAME,(GOODS_NUM * GOODS_PRICE) as totalPrice\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")) {
ResultSet resultSet = statement.executeQuery();
List<Order> list = new ArrayList<>();
while (resultSet.next()) {
Order order = new Order();
order.id = resultSet.getInt(1);
order.userName = resultSet.getString(2);
order.goodsName = resultSet.getString(3);
order.totalPrice = resultSet.getBigDecimal(4);
list.add(order);
}
return list;
}
}

// 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