[英]Relations in ER diagram
我正在尝试为软件开发公司创建数据库(作为免费项目)
我已经为此苦苦挣扎了很长时间了,是时候向你们寻求帮助了。
我有3个实体,PROGRAMMER,PROGRAM和PLATFORM。 程序员可以在许多平台上工作,程序可以在许多平台上工作,而程序员可以在许多程序上工作。 但是对于特定程序,程序员只能使用一个平台。 因此,我创建了另一个名为WORKS的表,该表具有以下属性:Programmer_ID,Program_ID和Platform_ID。 前两个是主键,因此符合上述规格。
现在,问题开始了:程序员可以监督一个程序(不是强制性的)。 监督小组开会,数据库必须存储每个程序的team_ID和会议的DATE,以及Meeting_ID,但这无关紧要。
因此,我必须制作一个不允许在Programmer_ID-Program_ID对上重复的表,以便同一个人第二次不会再在同一组中,而且还必须有一个Team_ID巫婆将与Program_ID,它必须将Team_ID引用到MEETING表中,以便我可以存储它。 我该怎么做?
感谢您的时间。
PS:这是我的ER外观: ER图
这是MS SQL 2012中导出的DLL:
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
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