Lecture 1 INSY 3304 - 002
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This 4 page Class Notes was uploaded by loveena Cherukunnathu on Saturday January 23, 2016. The Class Notes belongs to INSY 3304 - 002 at University of Texas at Arlington taught by Karen Scott in Spring 2016. Since its upload, it has received 93 views. For similar materials see Database Management Systems in Information technology at University of Texas at Arlington.
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Date Created: 01/23/16
January 22, 2016 Database Systems: Design, Implementation, and Management - Tenth Edition Chapter 1: Database Systems Data vs. Information Data Why do we need database? To store data and solve problems. Data is raw facts or observations that has little meaning on their own. It is the foundation of information. Information Information is data that has been processed/formatted to give it meaning and make it useful. We use processing to convert data into information. Introducing the Database Database Database is where you store data which is used to solve problems and produce reports. Data base is a shared integrated computer of structure that stores the collections of end-user data and metadata. o End-user data End user data is raw facts that are of interest to the end user. o Metadata Metadata is the data about the data (provides descriptions of the data – characteristics and relationships). Compliments and expands value of your data. Ex: each data, or description, of a customer is a metadata. Database management system (DBMS): DBMS manages the structure of data and control the access to the data. It can be one or more programs. It is the intermediary between user and the database. It provides for sharing or integration of data (ex: many users can use/share the data) Figure 1.2 shows How DBMS can manage. Front user (have an application that interacts with the backend process) DBMS is used to request the data data is collected and gives back to the user. All metadata and end user data is stored in DBMS DBMS can be used for the integration of the data and different views of the data (ex: the information sales associate needs is not what another department needs, so the data is shown differently to each department). Advantages of a DBMS It improves data sharing and data security. Ex: In excel there isn’t much security but DBMS has more security. DMBS allows better integration of data. Multiply people can work on the database at the same time. Different views to what they need. More data consistency. DBMS has a lot of code build into it that helps with this. Improves data access and better decision making. Increase end user productivity. (DBMS takes care of the details for you which makes it easier for the end-user) Types of Databases You have different vendors for database and you also have different types of databases. Databases classifications o Number of users o Database location(s) o Expected type and extent of use Number of users Single-user database: only one user at a time. (A.K.A. desktop database) Multi-user database: multiple users using the database at the same time. Work group database: a department or one small organization (less than 50 people) Enterprise database: multiple department, large companies (over 50 people) Location This is where the data is actually stored. Physical location is where data is stored (ex: in disk or the actual location) Logical location is how the user sees it. You can have a centralized location: all data at a single cite physically at one spot Decentralized location: data is distributed physically at different areas but logically viewed as single location. Type and Extent of Use Extent (A.K.A. transactional or productional database): operational database which support the companies day to day operations (ex: payroll, inventory). Data warehouse and decision support: for tactical or strategic decision making (ex: see what this company produced in long term and see if they should continue or not). All the long term data is stored here. We can store different data in these databases. Unstructured Unstructured is data that is in its original state. Structured Structure is data resulting from formatting. (we usually don’t store data like this) Semi-structured Semi-structured is in between both unstructured and structured. Data processed to some extent. Ex: some calculated that have total (but we can calculate the total anytime so why store data in this form?) or if we add “$” to money data (but it is not necessary to add it and store that data) XML XML is Extensible Markup Language. It represent data elements in textual format. XML format supports semi-structured XML data.(ex: you can use customized tag like <title><text>) Database Design What is it? Database design focuses on design on the database structure. This is the structure used for the end-user data. In order to produce a good design, the designer has to identify the expected use of data. Why necessary? It makes data management easier, generates accurate/valuable data; avoids hard to trace errors and redundant data. Database design is the foundation for all the data, and if u don’t do the design properly, you will have to do a lot more work to go around the problem. Evolution of File System Data Processing File systems Back in the day, people used file systems. For small companies it worked well, because they used to categorize properly. Its old fashion but we use this logic to store data in computer databases. File systems is composed of file folders, each tagged and kept in an area or network. Why study file systems? Studying file systems make complexity of database easier to understand, also helps in understanding how to convert from a file system to a database.
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