I am trying to create a database for a software development company (as a free time project)
I've been struggling with this for quite a while now, it's time to ask you guys for help.
I have 3 entities, PROGRAMMER, PROGRAM and PLATFORM. A programmer can work on many platforms, a program can be worked on many platforms and a programmer can work on many programs. BUT for a specific program the programmer can only work with one platform. So I created another table called WORKS witch has the following attributes: Programmer_ID, Program_ID and Platform_ID. The first two are Primary Keys so that it meets the specifications above.
Now, is where the problem starts: Programmers can supervise a program (it's not mandatory). The supervising team meets and the database has to store a team_ID for every program and a DATE for the meeting, also a Meeting_ID but that's irrelevant.
So, I have to make a table that doesn't allow duplicates on the pair Programmer_ID - Program_ID so that the same person wont be on the same group a second time, also it has to have a Team_ID witch will be the same number as the Program_ID and it has to reference the Team_ID to the MEETING table so I can store it. How can I do such a thing?
Thank you for your time.
PS: Here is how my ER looks: ER Diagram
And this is the exported DLL in MS SQL 2012:
CREATE
TABLE CUSTOMER
(
Customer_ID NUMERIC (5) NOT NULL ,
Name CHAR (30) NOT NULL ,
PR_Guy CHAR (30) NOT NULL ,
Phone CHAR (20) NOT NULL
)
ON "default"
GO
ALTER TABLE CUSTOMER ADD CONSTRAINT CUSTOMER_PK PRIMARY KEY CLUSTERED (
Customer_ID)
WITH
(
ALLOW_PAGE_LOCKS = ON ,
ALLOW_ROW_LOCKS = ON
)
ON "default"
GO
CREATE
TABLE KNOWS
(
Programmer_ID NUMERIC (5) NOT NULL ,
Prog_Lang_ID NUMERIC (3) NOT NULL
)
ON "default"
GO
ALTER TABLE KNOWS ADD CONSTRAINT KNOWS_PK PRIMARY KEY CLUSTERED (Programmer_ID,
Prog_Lang_ID)
WITH
(
ALLOW_PAGE_LOCKS = ON ,
ALLOW_ROW_LOCKS = ON
)
ON "default"
GO
CREATE
TABLE MEETING_DATE
(
Meeting_ID NUMERIC (3) NOT NULL ,
DATE DATE ,
Program_ID NUMERIC (5) ,
Programmer_ID NUMERIC (5)
)
ON "default"
GO
ALTER TABLE MEETING_DATE ADD CONSTRAINT MEETING_DATE_PK PRIMARY KEY CLUSTERED (
Meeting_ID)
WITH
(
ALLOW_PAGE_LOCKS = ON ,
ALLOW_ROW_LOCKS = ON
)
ON "default"
GO
CREATE
TABLE PLATFORM
(
Platform_ID NUMERIC (5) NOT NULL ,
Name CHAR (30) NOT NULL ,
OS CHAR (30) ,
Latest_Update DATE NOT NULL ,
Dev_Name CHAR (30) NOT NULL
)
ON "default"
GO
ALTER TABLE PLATFORM ADD CONSTRAINT PLATFORM_PK PRIMARY KEY CLUSTERED (
Platform_ID)
WITH
(
ALLOW_PAGE_LOCKS = ON ,
ALLOW_ROW_LOCKS = ON
)
ON "default"
GO
CREATE
TABLE PROGRAM
(
Program_ID NUMERIC (5) NOT NULL ,
Name CHAR (30) NOT NULL ,
Deadline DATE NOT NULL ,
Customer_ID NUMERIC (5) NOT NULL
)
ON "default"
GO
ALTER TABLE PROGRAM ADD CONSTRAINT PROGRAM_PK PRIMARY KEY CLUSTERED (Program_ID
)
WITH
(
ALLOW_PAGE_LOCKS = ON ,
ALLOW_ROW_LOCKS = ON
)
ON "default"
GO
CREATE
TABLE PROGRAMMER
(
Programmer_ID NUMERIC (5) NOT NULL ,
First_Name CHAR (30) NOT NULL ,
Last_Name CHAR (30) NOT NULL ,
Money_Status NUMERIC (1) NOT NULL
)
ON "default"
GO
ALTER TABLE PROGRAMMER ADD CONSTRAINT PROGRAMMER_PK PRIMARY KEY CLUSTERED (
Programmer_ID)
WITH
(
ALLOW_PAGE_LOCKS = ON ,
ALLOW_ROW_LOCKS = ON
)
ON "default"
GO
CREATE
TABLE PROG_LANG
(
Prog_Lang_ID NUMERIC (3) NOT NULL ,
Name CHAR (30) NOT NULL
)
ON "default"
GO
ALTER TABLE PROG_LANG ADD CONSTRAINT PROG_LANG_PK PRIMARY KEY CLUSTERED (
Prog_Lang_ID)
WITH
(
ALLOW_PAGE_LOCKS = ON ,
ALLOW_ROW_LOCKS = ON
)
ON "default"
GO
CREATE
TABLE SUPERVISE
(
Programmer_ID NUMERIC (5) NOT NULL ,
Program_ID NUMERIC (5) NOT NULL ,
Group_ID NUMERIC (5) NOT NULL
)
ON "default"
GO
ALTER TABLE SUPERVISE ADD CONSTRAINT SUPERVISE_PK PRIMARY KEY CLUSTERED (
Program_ID, Programmer_ID)
WITH
(
ALLOW_PAGE_LOCKS = ON ,
ALLOW_ROW_LOCKS = ON
)
ON "default"
GO
CREATE
TABLE WORKS
(
Programmer_ID NUMERIC (5) NOT NULL ,
Program_ID NUMERIC (5) NOT NULL ,
Platform_ID NUMERIC (5) NOT NULL
)
ON "default"
GO
ALTER TABLE WORKS ADD CONSTRAINT WORKS_PK PRIMARY KEY CLUSTERED (Programmer_ID,
Program_ID)
WITH
(
ALLOW_PAGE_LOCKS = ON ,
ALLOW_ROW_LOCKS = ON
)
ON "default"
GO
ALTER TABLE KNOWS
ADD CONSTRAINT FK_ASS_2 FOREIGN KEY
(
Programmer_ID
)
REFERENCES PROGRAMMER
(
Programmer_ID
)
ON
DELETE
NO ACTION ON
UPDATE NO ACTION
GO
ALTER TABLE KNOWS
ADD CONSTRAINT FK_ASS_3 FOREIGN KEY
(
Prog_Lang_ID
)
REFERENCES PROG_LANG
(
Prog_Lang_ID
)
ON
DELETE
NO ACTION ON
UPDATE NO ACTION
GO
ALTER TABLE MEETING_DATE
ADD CONSTRAINT MEETING_DATE_SUPERVISE_FK FOREIGN KEY
(
Program_ID,
Programmer_ID
)
REFERENCES SUPERVISE
(
Program_ID ,
Programmer_ID
)
ON
DELETE
NO ACTION ON
UPDATE NO ACTION
GO
ALTER TABLE PROGRAM
ADD CONSTRAINT PROGRAM_CUSTOMER_FK FOREIGN KEY
(
Customer_ID
)
REFERENCES CUSTOMER
(
Customer_ID
)
ON
DELETE
NO ACTION ON
UPDATE NO ACTION
GO
ALTER TABLE SUPERVISE
ADD CONSTRAINT SUPERVISE_WORKS_FK FOREIGN KEY
(
Programmer_ID,
Program_ID
)
REFERENCES WORKS
(
Programmer_ID ,
Program_ID
)
ON
DELETE
NO ACTION ON
UPDATE NO ACTION
GO
ALTER TABLE WORKS
ADD CONSTRAINT WORKS_PLATFORM_FK FOREIGN KEY
(
Platform_ID
)
REFERENCES PLATFORM
(
Platform_ID
)
ON
DELETE
NO ACTION ON
UPDATE NO ACTION
GO
ALTER TABLE WORKS
ADD CONSTRAINT WORKS_PROGRAMMER_FK FOREIGN KEY
(
Programmer_ID
)
REFERENCES PROGRAMMER
(
Programmer_ID
)
ON
DELETE
NO ACTION ON
UPDATE NO ACTION
GO
ALTER TABLE WORKS
ADD CONSTRAINT WORKS_PROGRAM_FK FOREIGN KEY
(
Program_ID
)
REFERENCES PROGRAM
(
Program_ID
)
ON
DELETE
NO ACTION ON
UPDATE NO ACTION
GO
Could not put this in a comment since there is an image to be shown.
If your WORKS table has a primary key that has all 3 i.e. PROGRAMMER_ID, PROGRAM_ID and PLATFORM_ID then the MEETING table can be a child of the WORKS table and that I think may address your issue.
See below diagram