Data Design in Software Engineering Assignment

Assignment Task

Data Design

• The Data Requirements of the IS we are developing were identified during the Analysis phase. These requirements need to be structured in an efficient form, so as to ensure data integrity and easy maintenance
• Traditional legacy systems relied on separate data files. Most current ISuse a DBMS.
• The most well-known type of DBMS is the Relational (RDBMS).
• Other types are Hierarchical Databases, Network Databases, Object-oriented Databases, Graph Databases, ER model Databases, and Document Databases.
• RDBMSs today have evolved a lot. They are secure, efficient, flexible and FREE for small systems.
• The data within a DBMS is accessed and maintained using a language, the most widely used is SQL (Structured Query Language) or Query by Example.

Tables & Keys in a DBMS

• The data within a DBMS is stored in tables which consist of rows and columns
• Each row represents a data record, e.g. a STUDENT record.
• In each column (often called fields) are stored individual data values, e.g student name, address, telephone number etc. Each column has a defined data type.
• Each row is identified by a Primary Key (PK). The PK makes it possible to retrieve a record very fast from a table of millions of records.

Definitions: Data Design Terms

Entity: An entity is a person, place, thing or event for which data is collected and maintained.eg: an online sales system may include entities named: CUSTOMER, ORDER, PRODUCT, or SUPPLIER.

Table or File: it contains a set of related records, where data is organized. Tables or Files are shown as 2-dimensional structures that consist of columns and rows.

Field: (or attribute) is a single characteristic or fact about an entity.eg: the entity CUSTOMER might have as fields the Name, Surname, Address, email etc.

Record: a record is a set of related fieldsthat describes an instance or occurrence of an entity such as one customer, product etc. It might have one or many fields.

Definitions: Key Fields

Primary Key: a Primary Key is a field or combination of keys that uniquely and minimally identifies a particular member of an entity

Candidate key: sometimes there is a choice of fields to use as a Primary Key (eg: choice between COURSE DESCR. and COURSE NO).

Foreign Key: is a field in one table that matches the Primary Key of another table (eg: ADVISOR NUMBER).

Secondary Key: is a field or combination of fields that is not unique, but can be used to access or sort or display records, for eg “the postal code”.

Case Study: Cyber Toys

Cyber Toys” is a small chain that sells computer hardware and software and specializes in personal service. The company has 4 stores located at malls and is planning more. Each store has a Manager, a technician, and between one and four sales reps. The owner wants to create a personnel records database. The Analyst suggests fields for store number, location, store tel, manager name, and manager home telephone. Also, fields for technician name + technician tel and fields for up to four sales rep names + sales rep tel.

Magic Maintenance

• The company “Magic Maintenance” provides on-site service for electronic equipment. The following slide provides the overall database design that such a firm might use. The DB consists of 7 separate tables, all joined by common fields, so they form an integral data structure.
• It’s a relational database.

Questions

1. Did any customers receive service after 5/4/2015? Who were they?

2. Did technician Marie Johnson put in more than 6 hours of labor on any service calls? Which ones?

3. Were any parts used on service calls in Washington? Is so, list the part numbers, descriptions, and quantities.

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