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Stragling with homework. Could anybody help , please.
I know sounds fanny, but i got problem with understanding Database design in
Access. I 've read ten times tutorials but nothing helps. This is content of homework: All students are enrolled on courses, each student on one course only. Students register for modules and the list of students enrolled for each module in each semester is held in the Module Register which also holds information about which tutorial group the student is in and the marks of the students achieved in the coursework and examination assessment. The Programme of Study holds information specifying which modules are core or designated for the course. Each course also has modules and subject lecturers for that course. One course can contain many modules and one module can be a part of one course only. The text above contains information that needs to be stored in a database. For that purpose, do the following tasks (please note that Tasks 1 and 2 are done on paper before you even open MS Access): 1. From the text above identify the rest of the entities and their attributes that are relevant to the University Database. Example: Student as an entity has characteristics (attributes) such as RegNo, LastName, FirstName, Age, Initials, DateEnrolled. 2. Entities and attributes identified in Task 1 can be stored in various tables that share common information. The tables can be linked through relationships. Eg. Student has to enrol on a course, So there is a relationship between the tables Student and Course. Determine the relationships between the entities (tables) identified above If anybody wants to help me , at least to give direction how to start ,i 'd be glad. -- azik |
#2
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Azik,
I think it's important that you struggle with it yourself, but to get you oriented... First, start by not worrying about data structures, or the limiting factors, etc. Those are details you can flesh out later. First think in terms of Things, and Adjectives that describe these things (what your professor calls Entities and Attributes--why academics use big words when small ones will do is a mystery to me!). The Things will become tables, and their Adjectives fields in the tables. In your case, I can think of the following things: Students Modules Courses TutorialGroups Then, attempt to flesh out the adjectives. Your prof has given you a start below. Now, think in terms of relationships. There are 2 basic ones--one-to-many, and many-to-many. A one-to-one normally can be implemented simply by making a single table. There are exceptions, but they are beyond your assignment scope. In any case, a one-to-one is really just a special case of a one-to-many. If you discover a many-to-many relationship, you will need another table, because a many-to-many can be implemented by two one-to-many relationships. For example, in an Order Entry database, there is a many-to-many relationship between Customers and OrderDetails. Many customers can order the same product, and each customer can order many products. Now, as your prof has probably described to you, you in almost every case don't want any fields in a table that are already defined in another table, EXCEPT the one that corresponds to that table's primary key(PK), called a foreign key (FK). For example, a Customer table would have a customer number(primary key), name, address, phone, etc.. To enter an order, you'd need to identify it with a certain customer, so you would include a customer number field in your Orders table (a foreign key), but NOT their phone, address, name, or any other Customer field. Access is named for a reason, relational databases, by using foreign keys, give you access to any field in a related table. If you get this clear, you're on your way, because 25-50% of the questions on this newsgroup relate to this concept. In the Order Entry example above, the missing table that converts the many-to-many to two one-to-many's is the Orders table. It would have an order number(PK), the customer number (FK to Customers), the date the order was placed, the code for the salesperson who took the order (FK to Salespersons), and perhaps a Shipping Code (FK to ShippingMethods). The OrderDetails would have a ProductID (FK to Products), a Qty, and a UnitPrice. The UnitPrice field, by the way, is an exception to duplicating fields from one table across another, because we have to capture the UnitPrice from the Products table at the time of the order, otherwise the Order record would be incorrect after we changed prices down the road. Good luck. Hope that gets you started. Sprinks "azik" wrote: I know sounds fanny, but i got problem with understanding Database design in Access. I 've read ten times tutorials but nothing helps. This is content of homework: All students are enrolled on courses, each student on one course only. Students register for modules and the list of students enrolled for each module in each semester is held in the Module Register which also holds information about which tutorial group the student is in and the marks of the students achieved in the coursework and examination assessment. The Programme of Study holds information specifying which modules are core or designated for the course. Each course also has modules and subject lecturers for that course. One course can contain many modules and one module can be a part of one course only. The text above contains information that needs to be stored in a database. For that purpose, do the following tasks (please note that Tasks 1 and 2 are done on paper before you even open MS Access): 1. From the text above identify the rest of the entities and their attributes that are relevant to the University Database. Example: Student as an entity has characteristics (attributes) such as RegNo, LastName, FirstName, Age, Initials, DateEnrolled. 2. Entities and attributes identified in Task 1 can be stored in various tables that share common information. The tables can be linked through relationships. Eg. Student has to enrol on a course, So there is a relationship between the tables Student and Course. Determine the relationships between the entities (tables) identified above If anybody wants to help me , at least to give direction how to start ,i 'd be glad. -- azik |
#3
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Hello,
I really shocked . I didn't believe , I will get any reply. This short explanation more then enough. It's very helpful and engouraging. Thank you very much for your help. |
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