问题
I am a new web developer and I am developing a simple training management system which provides the users with quizzes. The system developed using ASP.NET and MS SQLServer. Now, I need to come up with a query that shows the percentage of participation of each division in all the offered safety quizzes (which means quizzes with IsSent = true).
I have the following database design:
Employee Table: Username, Name, DivisionCode
Divisions Table: SapCode, Divison
Quiz Table: QuizID, Title, Description, IsSent
UserQuiz: UserQuizID, QuizID, DateTimeComplete, Username
(DivisionCode is a foreign key to the SapCode. IsSent is a flag to indicate to the quizzes that have been offered and sent to the users to participate in them.)
For example, If I have four divisions; A, B, C and D, and I have around 23 quizzes have been sent to the employees in those divisions. Since each division has a specific percentage of participation in each quiz. My query should show the overall percentage of participation in all offered quizzes for each division. So the result should not be broken down with respect to each quiz.
So how to do that?
And here's the schema of the database with its data:
USE [Test]
GO
/****** Object: Table [dbo].[Divisions] Script Date: 08/03/2012 19:36:09 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Divisions](
[SapCode] [nvarchar](50) NOT NULL,
[Division] [varchar](50) NOT NULL,
CONSTRAINT [PK_Divisions] PRIMARY KEY CLUSTERED
(
[SapCode] 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
SET ANSI_PADDING OFF
GO
INSERT [dbo].[Divisions] ([SapCode], [Division]) VALUES (N'1', N'A')
INSERT [dbo].[Divisions] ([SapCode], [Division]) VALUES (N'2', N'B')
INSERT [dbo].[Divisions] ([SapCode], [Division]) VALUES (N'3', N'C')
/****** Object: Table [dbo].[Quiz] Script Date: 08/03/2012 19:36:09 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Quiz](
[QuizID] [int] IDENTITY(1,1) NOT NULL,
[Title] [varchar](50) NOT NULL,
[Description] [varchar](50) NOT NULL,
[IsSent] [bit] NOT NULL,
CONSTRAINT [PK_Quiz] PRIMARY KEY CLUSTERED
(
[QuizID] 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
SET ANSI_PADDING OFF
GO
SET IDENTITY_INSERT [dbo].[Quiz] ON
INSERT [dbo].[Quiz] ([QuizID], [Title], [Description], [IsSent]) VALUES (1, N'Quiz I', N'Test', 1)
INSERT [dbo].[Quiz] ([QuizID], [Title], [Description], [IsSent]) VALUES (2, N'Quiz II', N'Test test', 1)
INSERT [dbo].[Quiz] ([QuizID], [Title], [Description], [IsSent]) VALUES (3, N'Quiz III', N'TEST TEST', 0)
SET IDENTITY_INSERT [dbo].[Quiz] OFF
/****** Object: Table [dbo].[Employee] Script Date: 08/03/2012 19:36:09 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Employee](
[Usename] [nvarchar](50) NOT NULL,
[Name] [varchar](50) NOT NULL,
[DivisionCode] [nvarchar](50) NOT NULL,
CONSTRAINT [PK_Employee] PRIMARY KEY CLUSTERED
(
[Usename] 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
SET ANSI_PADDING OFF
GO
INSERT [dbo].[Employee] ([Usename], [Name], [DivisionCode]) VALUES (N'John12', N'John A', N'1')
INSERT [dbo].[Employee] ([Usename], [Name], [DivisionCode]) VALUES (N'John13', N'John B', N'1')
INSERT [dbo].[Employee] ([Usename], [Name], [DivisionCode]) VALUES (N'John15', N'John C', N'3')
INSERT [dbo].[Employee] ([Usename], [Name], [DivisionCode]) VALUES (N'Maria12', N'Maria A', N'3')
INSERT [dbo].[Employee] ([Usename], [Name], [DivisionCode]) VALUES (N'Rony14', N'Rony A', N'2')
INSERT [dbo].[Employee] ([Usename], [Name], [DivisionCode]) VALUES (N'Tid52', N'Tid A', N'3')
INSERT [dbo].[Employee] ([Usename], [Name], [DivisionCode]) VALUES (N'Tim12', N'Tim A', N'1')
INSERT [dbo].[Employee] ([Usename], [Name], [DivisionCode]) VALUES (N'Tim15', N'Tim B', N'2')
/****** Object: Table [dbo].[UserQuiz] Script Date: 08/03/2012 19:36:09 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[UserQuiz](
[UserQuizID] [int] IDENTITY(1,1) NOT NULL,
[QuizID] [int] NOT NULL,
[DateTimeComplete] [datetime] NOT NULL,
[Score] [float] NOT NULL,
[Username] [nvarchar](50) NOT NULL,
CONSTRAINT [PK_UserQuiz] PRIMARY KEY CLUSTERED
(
[UserQuizID] 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
SET IDENTITY_INSERT [dbo].[UserQuiz] ON
INSERT [dbo].[UserQuiz] ([UserQuizID], [QuizID], [DateTimeComplete], [Score], [Username]) VALUES (1, 1, CAST(0x0000A07900000000 AS DateTime), 100, N'John12')
INSERT [dbo].[UserQuiz] ([UserQuizID], [QuizID], [DateTimeComplete], [Score], [Username]) VALUES (2, 1, CAST(0x0000A07900000000 AS DateTime), 50, N'Tim12')
INSERT [dbo].[UserQuiz] ([UserQuizID], [QuizID], [DateTimeComplete], [Score], [Username]) VALUES (3, 1, CAST(0x0000A07B00000000 AS DateTime), 100, N'Rony14')
INSERT [dbo].[UserQuiz] ([UserQuizID], [QuizID], [DateTimeComplete], [Score], [Username]) VALUES (4, 1, CAST(0x0000A07900000000 AS DateTime), 0, N'Tim15')
INSERT [dbo].[UserQuiz] ([UserQuizID], [QuizID], [DateTimeComplete], [Score], [Username]) VALUES (5, 1, CAST(0x0000A07900000000 AS DateTime), 100, N'Tid52')
SET IDENTITY_INSERT [dbo].[UserQuiz] OFF
/****** Object: ForeignKey [FK_Employee_Divisions] Script Date: 08/03/2012 19:36:09 ******/
ALTER TABLE [dbo].[Employee] WITH CHECK ADD CONSTRAINT [FK_Employee_Divisions] FOREIGN KEY([DivisionCode])
REFERENCES [dbo].[Divisions] ([SapCode])
GO
ALTER TABLE [dbo].[Employee] CHECK CONSTRAINT [FK_Employee_Divisions]
GO
/****** Object: ForeignKey [FK_UserQuiz_Employee] Script Date: 08/03/2012 19:36:09 ******/
ALTER TABLE [dbo].[UserQuiz] WITH CHECK ADD CONSTRAINT [FK_UserQuiz_Employee] FOREIGN KEY([Username])
REFERENCES [dbo].[Employee] ([Usename])
GO
ALTER TABLE [dbo].[UserQuiz] CHECK CONSTRAINT [FK_UserQuiz_Employee]
GO
/****** Object: ForeignKey [FK_UserQuiz_Quiz] Script Date: 08/03/2012 19:36:09 ******/
ALTER TABLE [dbo].[UserQuiz] WITH CHECK ADD CONSTRAINT [FK_UserQuiz_Quiz] FOREIGN KEY([QuizID])
REFERENCES [dbo].[Quiz] ([QuizID])
GO
ALTER TABLE [dbo].[UserQuiz] CHECK CONSTRAINT [FK_UserQuiz_Quiz]
GO
UPDATE: The results should be like this:
Division ************* Overall Percentage
A **************** 80
B **************** 60
C **************** 50
And the overall percentage is the total of all percent completion of each division in each quiz. For instance, the percent completion for division A in Quiz#1 = 40%, and in Quiz#2 = 60% and in Quiz#3 = 90%, the overall percentage that should be shown by this query is the total of all the of them divided by the total number of sent quizzes (which is 3). I hope I am clear and the concept is obvious.
UPDATE #2:
I am still struggling with it but I came up with a query that shows the total number of employees and participants in each quiz for each division. And here's the query:
SELECT COUNT(dbo.Employee.Usename) AS [Total Number of Employees], COUNT(dbo.UserQuiz.Username) AS [Total Number of Participants], dbo.Divisions.Division,
dbo.Quiz.Title
FROM dbo.Divisions INNER JOIN
dbo.Employee ON dbo.Divisions.SapCode = dbo.Employee.DivisionCode INNER JOIN
dbo.UserQuiz ON dbo.Employee.Usename = dbo.UserQuiz.Username INNER JOIN
dbo.Quiz ON dbo.UserQuiz.QuizID = dbo.Quiz.QuizID
WHERE (dbo.Quiz.IsSent = 1)
GROUP BY dbo.Divisions.Division, dbo.Quiz.Title
What should I do to improve it and get what I need?
回答1:
The following query may do what you want. I calculates the number of employees in each division, multiplies this by the number of quizzes. It then divides the number actually taken by this total:
select de.Division, de.numemployees, de.numemployees*q.numquizzes as qe_combos,
numquizzestaken/1.0*de.numemployees*q.numquizzes as proportion
from (select d.Division, count(*) as numemployees
from Employee e join
Division d
on e.DivisionCode = d.SapCode
group by d.Division
) de left outer join
(select d.Division, count(*) as numquizzestaken
from Employee e join
Division d
on e.DivisionCode = d.SapCode join
UserQuiz uq
on e.UserName = uq.UserName join
Quiz q
on uq.QuidId = q.QuizId and
q.issent = true
group by de.Division
) dq
on de.division = dq.division cross join
(select count(*) as numquizes
from Quiz q
where isSent = true
) q
来源：https://stackoverflow.com/questions/11799899/how-to-show-the-overall-percentage-of-participation-of-each-division-in-all-sent