February 11, 2009 at 9:11 am
I have the following Data:
InstructorsCourse ID ClassCompany Room
Dan Smith100 AJAXAmerican Airlines500
Dianne Ross200 WPFBoeing 502
Donna White300 LINQLufthansa500
Donna White100 AJAXLufthansa501
There is a one to many relationship between room and course (1 room can have
many courses)
There is a one to many relationship between Course and Teacher (1 course can be
taught by many teachers)
There is also Many to Many relationship between Company and Class
How would I design the database?
February 11, 2009 at 9:17 am
Hmm... This looks an awful lot like homework. Why don't you post what you think the design should look like and maybe someone will critique it?
Greg
February 11, 2009 at 9:31 am
DanCafeFood (2/11/2009)
IThere is a one to many relationship between room and course (1 room can have
many courses)
There is a one to many relationship between Course and Teacher (1 course can be
taught by many teachers)
There is also Many to Many relationship between Company and Class
How would I design the database?
It looks like you already a have the basic table srtuctures defined in the statement above. You have rooms (table names should always be plural), teachers, courses (I'm assuming courses and classes are the same), and companies. Then you just need to define your relationships. A search on Many To Many relationship in database design will return many resources.
As Greg said, post what your ideas and folks will comment on them.
Jack Corbett
Consultant - Straight Path Solutions
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February 11, 2009 at 9:52 am
I wanted to paste the database diagram picture here. Is there a way to paste it.
February 11, 2009 at 10:25 am
I guess there is no way to paste a database diagram here, so here is my idea:
CREATE TABLE [dbo].[tblClass](
[ClassName] [nchar](10) NULL,
[RoomName] [nchar](10) NULL
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[tblClass] ADD CONSTRAINT [PK_ClassName] PRIMARY KEY CLUSTERED
(
[ClassName] ASC
)GO
CREATE TABLE [dbo].[tblCompany](
[CompanyID] [nchar](10) NULL,
[CompanyName] [nchar](10) NULL
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[tblCompany] ADD CONSTRAINT [PK_CompanyID] PRIMARY KEY CLUSTERED
(
[CompanyID] ASC
)GO
CREATE TABLE [dbo].[tblRooms](
[RoomName] [nchar](10) NULL
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[tblCompany] ADD CONSTRAINT [PK_RoomName] PRIMARY KEY CLUSTERED
(
[RoomName] ASC
)GO
CREATE TABLE [dbo].[tblTeachers](
[CompanyId] [nchar](10) NULL,
[Teacher] [nchar](10) NULL
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[tblTeachers] ADD CONSTRAINT [PK_Teacher] PRIMARY KEY CLUSTERED
(
[Teacher] ASC
)GO
CREATE TABLE [dbo].[tblCompClass](
[CompanyId] [nchar](10) NULL,
[ClassID] [nchar](10) NULL
) ON [PRIMARY]
GO
ALTER TABLE [dbo].tblCompClass] WITH CHECK ADD CONSTRAINT [FK_tblCompClass_Company] FOREIGN KEY([CompanyID])
REFERENCES [dbo].[tblCompany] ([CompanyID])
GO
ALTER TABLE [dbo].[tblCompClass] CHECK CONSTRAINT [FK_tblCompClass_Company]
GO
ALTER TABLE [dbo].[tblCompClass] WITH CHECK ADD CONSTRAINT [FK_tblCompClass_tblClass] FOREIGN KEY([ClassName])
REFERENCES [dbo].[tblClass] ([ClassName])
GO
ALTER TABLE [dbo].[tblCompClass] CHECK CONSTRAINT [FK_tblCompClass_tblClass]
GO
ALTER TABLE [dbo].[tblTeacher] WITH CHECK ADD CONSTRAINT [FK_tblTeacher_tblCompany] FOREIGN KEY([CompanyID])
REFERENCES [dbo].[tblCompany] ([CompanyID])
GO
ALTER TABLE [dbo].[tblTeacher] CHECK CONSTRAINT [FK_tblTeacher_tblCompany]
GO
ALTER TABLE [dbo].[tblClass] WITH CHECK ADD CONSTRAINT [FK_tblClass_tblRooms] FOREIGN KEY([RoomName])
REFERENCES [dbo].[tblRooms] ([RoomName])
GO
ALTER TABLE [dbo].[tblClass] CHECK CONSTRAINT [FK_tblClass_tblRooms]
GO
February 11, 2009 at 10:46 am
Looks like it would work. One of my preferences is to to use an identity column as the primary key (adding a unique constraint on the true primary key) and then use that id column as the foreign key in other tables. If you do not do this and room names can change you need to make sure CASCADE updates on your relationships.
Jack Corbett
Consultant - Straight Path Solutions
Check out these links on how to get faster and more accurate answers:
Forum Etiquette: How to post data/code on a forum to get the best help
Need an Answer? Actually, No ... You Need a Question
February 11, 2009 at 10:50 am
Jack,
Thanks for the reply. It makes sense to add the ID identity column in Rooms table. My question is, does this design looks too normalized?
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