From 51e4cf4deac34d02bda1717460407ffbec1b4fff Mon Sep 17 00:00:00 2001 From: lance <491799643@qq.com> Date: Sun, 31 May 2020 09:45:14 +0800 Subject: [PATCH 1/3] =?UTF-8?q?select=E8=AF=AD=E5=8F=A5=E5=AE=9E=E6=88=98?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- src/main/java/com/github/hcsp/sql/Sql.java | 84 +++++++++++++++++++--- 1 file changed, 76 insertions(+), 8 deletions(-) diff --git a/src/main/java/com/github/hcsp/sql/Sql.java b/src/main/java/com/github/hcsp/sql/Sql.java index 418a0df..554d0c3 100644 --- a/src/main/java/com/github/hcsp/sql/Sql.java +++ b/src/main/java/com/github/hcsp/sql/Sql.java @@ -2,9 +2,8 @@ package com.github.hcsp.sql; import java.io.File; import java.math.BigDecimal; -import java.sql.Connection; -import java.sql.DriverManager; -import java.sql.SQLException; +import java.sql.*; +import java.util.ArrayList; import java.util.List; public class Sql { @@ -82,7 +81,16 @@ public String toString() { // | 2 | // +-----+ public static int countUsersWhoHaveBoughtGoods(Connection databaseConnection, Integer goodsId) throws SQLException { - return 0; + String sql = "select count(distinct user_id) from \"ORDER\" where goods_id = ? ;"; + try(PreparedStatement preparedStatement = databaseConnection.prepareStatement(sql)) { + preparedStatement.setInt(1, goodsId); + ResultSet resultSet = ((PreparedStatement) preparedStatement).executeQuery(); + if (resultSet.next()) { + return resultSet.getInt(1); + } else { + return -1; + } + } } /** @@ -100,7 +108,22 @@ public static int countUsersWhoHaveBoughtGoods(Connection databaseConnection, In // | 1 | zhangsan | tel1 | beijing | // +----+----------+------+----------+ public static List getUsersByPageOrderedByIdDesc(Connection databaseConnection, int pageNum, int pageSize) throws SQLException { - return null; + List userList = new ArrayList<>(); + String sql = "select * from user order by id desc limit ?,?; "; + try (PreparedStatement preparedStatement = databaseConnection.prepareStatement(sql)) { + preparedStatement.setInt(1, (pageNum - 1) * pageSize); + preparedStatement.setInt(2, pageSize); + ResultSet resultSet = preparedStatement.executeQuery(); + 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); + userList.add(user); + } + } + return userList; } // 商品及其营收 @@ -132,7 +155,22 @@ public String toString() { // | 3 | goods3 | 20 | // +----+--------+------+ public static List getGoodsAndGmv(Connection databaseConnection) throws SQLException { - return null; + List goodsAndGmvList = new ArrayList<>(); + try (PreparedStatement statement = databaseConnection.prepareStatement("select GOODS_ID, GOODS.NAME, sum(GOODS_NUM * GOODS_PRICE) as total\n" + + "from `ORDER`\n" + + " join GOODS on `ORDER`.GOODS_ID = GOODS.ID\n" + + "group by GOODS_ID\n" + + "order by total desc")) { + ResultSet resultSet = statement.executeQuery(); + while (resultSet.next()) { + GoodsAndGmv goodsAndGmv = new GoodsAndGmv(); + goodsAndGmv.goodsId = resultSet.getInt(1); + goodsAndGmv.goodsName = resultSet.getString(2); + goodsAndGmv.gmv = resultSet.getBigDecimal(3); + goodsAndGmvList.add(goodsAndGmv); + } + } + return goodsAndGmvList; } @@ -170,7 +208,22 @@ public String toString() { // | 6 | zhangsan | goods3 | 20 | // +----------+-----------+------------+-------------+ public static List getInnerJoinOrders(Connection databaseConnection) throws SQLException { - return null; + List orderList = new ArrayList<>(); + try (PreparedStatement statement = databaseConnection.prepareStatement("select \"ORDER\".ID, U.NAME, G.NAME, GOODS_NUM * GOODS_PRICE\n" + + "from `ORDER`\n" + + " join USER U on `ORDER`.USER_ID = U.ID\n" + + " join GOODS G on `ORDER`.GOODS_ID = G.ID")) { + ResultSet resultSet = statement.executeQuery(); + 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); + orderList.add(order); + } + } + return orderList; } /** @@ -198,7 +251,22 @@ public static List getInnerJoinOrders(Connection databaseConnection) thro // | 8 | NULL | NULL | 60 | // +----------+-----------+------------+-------------+ public static List getLeftJoinOrders(Connection databaseConnection) throws SQLException { - return null; + List orderList = new ArrayList<>(); + try (PreparedStatement statement = databaseConnection.prepareStatement("select \"ORDER\".ID, U.NAME, G.NAME, GOODS_NUM * GOODS_PRICE\n" + + "from `ORDER`\n" + + " left join USER U on `ORDER`.USER_ID = U.ID\n" + + " left join GOODS G on `ORDER`.GOODS_ID = G.ID")) { + ResultSet resultSet = statement.executeQuery(); + 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); + orderList.add(order); + } + } + return orderList; } // 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 From 95666fd0aeb00507d4ce633dc53e63756232193f Mon Sep 17 00:00:00 2001 From: lance <491799643@qq.com> Date: Sun, 31 May 2020 09:58:22 +0800 Subject: [PATCH 2/3] =?UTF-8?q?select=E8=AF=AD=E5=8F=A5=E5=AE=9E=E6=88=98?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- src/main/java/com/github/hcsp/sql/Sql.java | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/main/java/com/github/hcsp/sql/Sql.java b/src/main/java/com/github/hcsp/sql/Sql.java index 554d0c3..62c22a9 100644 --- a/src/main/java/com/github/hcsp/sql/Sql.java +++ b/src/main/java/com/github/hcsp/sql/Sql.java @@ -84,7 +84,7 @@ public static int countUsersWhoHaveBoughtGoods(Connection databaseConnection, In String sql = "select count(distinct user_id) from \"ORDER\" where goods_id = ? ;"; try(PreparedStatement preparedStatement = databaseConnection.prepareStatement(sql)) { preparedStatement.setInt(1, goodsId); - ResultSet resultSet = ((PreparedStatement) preparedStatement).executeQuery(); + ResultSet resultSet = preparedStatement.executeQuery(); if (resultSet.next()) { return resultSet.getInt(1); } else { From 7daf3a4e89df33425e53ab9a479d7b5f396a6e9c Mon Sep 17 00:00:00 2001 From: lance <491799643@qq.com> Date: Sun, 31 May 2020 10:10:09 +0800 Subject: [PATCH 3/3] =?UTF-8?q?select=E8=AF=AD=E5=8F=A5=E5=AE=9E=E6=88=98?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- src/main/java/com/github/hcsp/sql/Sql.java | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/main/java/com/github/hcsp/sql/Sql.java b/src/main/java/com/github/hcsp/sql/Sql.java index 62c22a9..0b1a44d 100644 --- a/src/main/java/com/github/hcsp/sql/Sql.java +++ b/src/main/java/com/github/hcsp/sql/Sql.java @@ -1,5 +1,6 @@ package com.github.hcsp.sql; + import java.io.File; import java.math.BigDecimal; import java.sql.*; @@ -82,7 +83,7 @@ public String toString() { // +-----+ public static int countUsersWhoHaveBoughtGoods(Connection databaseConnection, Integer goodsId) throws SQLException { String sql = "select count(distinct user_id) from \"ORDER\" where goods_id = ? ;"; - try(PreparedStatement preparedStatement = databaseConnection.prepareStatement(sql)) { + try (PreparedStatement preparedStatement = databaseConnection.prepareStatement(sql)) { preparedStatement.setInt(1, goodsId); ResultSet resultSet = preparedStatement.executeQuery(); if (resultSet.next()) { @@ -97,7 +98,7 @@ public static int countUsersWhoHaveBoughtGoods(Connection databaseConnection, In * 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 */