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

Define two-phase locking protocol. Ans: Two-phase locking is significance in the context of ensuring that schedules are serializable. The two-phase locking protocol defines a p

Consider the following database schema: STAFF(StaffNo, fName, lName, Position, sex, dob, branchNo) BRANCH(BranchNo, Street, City) Assume the following for the above database

Let us now talk about the relational operations: SELECT The select operation is used to select few specific record from the database based on different criteria, This is a un


Company XYZ is an advertising company. It has its own website but the search facilities offered are not reliable. The company is willing to invest to acquire new machines and sof

crete a data base relationship model Entity: Students; Professors; Dormitories buildings; Attributes of students: Name; Address; Dorm;

The clause in SQL which specifies that the query result should be sorted in ascending or descending order based upon the values of one or much more columns is Ans : Order by

Ask question #MinimRead Dennis et al. Chapter 6: Minicase 2. Work through it and answer the questions. See the attached example. SequenceDiagram.png Based on the structural mod

Define page. The database is partitioned into some number of fixed-length blocks, which are referred to as pages.