Draw an er diagram with primary key for a farm, Database Management System

Draw an ER diagram that represents the information described below. Show all entity sets, relationship sets, primary keys, and the mapping cardinality of the relationship sets.

"Farmers own one or more sections of land, on which one or many types of grain (e.g., canola, rye, wheat, etc.) may be grown. The grain type can be uniquely identified by its grain ID. As each land section is owned by a single farmer, the farmer knows the amount of each type of grain (measured in tonnes) that is grown in each land section. Based on this information, the farmer can compute the total amount of grains grown in each land section. Each farmer has a name (consists of first name, middle initial, and last name) as well as a unique farmer ID, and may have several contact phone numbers.

When the grains are harvested, each farmer makes a contract to sell some of his grain to a specific grain pool (distribution centre). There are many pools, but each pool handles only one specific type of grain. The price per tonne is constant for each individual pool. There may be multiple pools handling the same type of grain. Normally, a farmer has a contract with a specific pool for a specific amount of a specific type of grain handled by that pool. However, a farmer may have contracts with many pools. Each pool then contracts with a business to sell a specific quantity of grain to that business at an agreed-upon price. This price may vary from contract to contract. A pool may have any number of contracts with any number of businesses, including multiple contracts with the same business. Each pool must maintain the total amount of grain that it has purchased from all of its farmers and the total amount of grain that it has contracted to sell."

Hint: For this question, you may assume the following:

(a) Each land section can be uniquely identified by its section ID. Given a section ID, one can easily find the dimension of the land section.

(b)  One or many types of grain may be grown on the same land section, and the same type of grain may be grown on different land sections.

(c)  Given a grain ID, one can identify the name of the grain type (e.g., canola, rye, wheat, etc.).

(d)  A grain pool (distribution centre) can be uniquely identified by its pool ID.

(e)  Several farmers may have contracts with the same pool.

(f)  A business can be uniquely identified by its business ID.

Posted Date: 2/28/2013 6:17:32 AM | Location : United States







Related Discussions:- Draw an er diagram with primary key for a farm, Assignment Help, Ask Question on Draw an er diagram with primary key for a farm, Get Answer, Expert's Help, Draw an er diagram with primary key for a farm Discussions

Write discussion on Draw an er diagram with primary key for a farm
Your posts are moderated
Related Questions
What are the physical characteristics of magnetic disks?   Ans: A magnetic disk is a circular plate or platter of plastic or metal that is coated with magnetizable material lik

Question: (a) List four disadvantages of the File Processing System as compared to the Database Systems. (b) The integrity of a database is enforced by integrity rules. One

Question : (a) Explain with the help of appropriate examples the difference between ‘Data' and ‘Information'. (b) A digital image is an array of pixels, where each pixel h

NEED FOR A DATABASE MANAGEMENT SYSTEM A Database is a structured, persistent collection of data of an organisation. The database management system (DBMS) manages the database o

Define Hash files organization a. Hashing includes computing the address of a data item by calculating a function on the search key value.   b. A hash function h is a functi

Define the Two Phase Locking Protocol This is a protocol that is used to make sure serializability of transactions. This protocol needs that every transaction issue lock and u

What is meant by heuristic optimisation?  Discuss the main heuristics that are applied during query optimisation.  Ans:  In heuristic optimization, heuristics are employed to r

After going by the database architecture, let us now dwell on an important query: how is the data organised in a database? There are a lot of basic structures that exist in a datab

#question benefits and limitations of data models..

what is difference between circular inked lust and grunded linked list