Experiments on an Olympiad problem

Wed, 03 May 2017 00:00:00 +0000

Introduction

It so happened that I got into graduate school, and while walking past the department, I stumbled upon an Olympiad problem on 1C. In short, the problem sounds like this: ‘There are sales records for each day, you need to find the longest period when the plan was executed.’ And then, while walking with my sleeping daughter, I had a question, how many ways can this be done in SQL? Solutions will be based on MS SQL."

Эксперименты над олимпиадной задачей

Wed, 03 May 2017 00:00:00 +0000

Предисловие

Так получилось, что я попал в магистратуру, и как то гуляя мимо кафедры на глаза попалась олимпиадная задача по 1С. Кратко задача звучит так: “Есть записи продажи за каждый день, необходимо найти наибольший период когда план выполнялся”. А потом когда я гулял со спящей дочкой у меня встав вопрос, а сколькими способами это можно сделать на SQL. Решения будут на основе MS SQL.

Создадим таблицу и начнем

CREATE TABLE [tmp].[forFindDate](
	[date] [datetime] NOT NULL,
	[value] [int] NOT NULL,
 CONSTRAINT [PK_forFindDate] PRIMARY KEY CLUSTERED 
(
	[date] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170401', 10)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170402', 20)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170403', 20)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170404', 20)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170405', 10)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170406', 10)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170407', 30)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170408', 36)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170409', 35)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170410', 30)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170411', 30)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170412', 20)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170413', 10)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170414', 40)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170415', 40)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170416', 10)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170417', 50)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170418', 52)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170419', 53)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170420', 53)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170421', 50)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170422', 51)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170423', 52)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170424', 50)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170425', 50)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170426', 50)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170427', 10)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170428', 10)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170429', 10)
INSERT INTO [tmp].[forFindDate] ([date], [value]) VALUES ('20170430', 10)

GO

Первый способ

SQl запросы через join на самого себя

Sql on Pavel Karasov

Experiments on an Olympiad problem

Introduction

Эксперименты над олимпиадной задачей

Предисловие

Первый способ