Lecture 1 Introduction to Database (updated 04/09/2016)

Objectives In this chapter, you will learn: Data vs information What a database is? Database Management System File Systems and Databases

Data vs Information

Data vs. Information Data (singular or plural) are raw facts Raw data - Not yet been processed to reveal the meaning Building blocks of information Information requires context to reveal meaning Eg, 123° 43' 52.12588" W Raw data must be formatted for storage, processing, and presentation Data are the foundation of information, which is the bedrock of knowledge

Data vs. Information (cont’d.) Information produced by processing data Information used to reveal meaning in data Accurate, relevant, timely information is the key to good decision making Good decision making is the key to organizational survival Data management: focuses on proper generation, storage, and retrieval of data

Why do I care about databases? Good decisions require good information derived from raw facts Data is managed most efficiently when stored in a database Databases solve many of the problems encountered in data management Used in almost all modern settings involving data management: Business Research Administration Important to understand how databases work and interact with other applications

What a database is?

What a Database is? A database is a collection of organized data which are collected over time. The data contains both user data and metadata. User data: raw facts of interest to end user They are student names, grades, salary etc. Metadata: data about data They are data type, relationship, date created, data modified, and file size and etc. Metadata also known as system catalog and data dictionary Database management system (DBMS) Is a collection of software Manages the database structure Controls access to data stored in the database More on this later

Database Management System

What is a Database Management System (DBMS)? An integrated database environment DBMS controls the access to the databases DBMS eliminates most of file system’s problems Current generation DBMS software: Stores data structures, relationships between structures, and access paths Defines, stores, and manages all access paths and components Logically related data stored in a single logical data repository Physically distributed among multiple storage facilities

Role of the DBMS Serve data to end user Interact DBMS directly or indirectly Use SQL to retrieve the data from the DBMS Allow writing applications for other users Java, C, C++, C# … Allow designing, creating and maintaining the database with ease Carry out the task by database administrator (DBA)

The Database System Environment

Advantages of Database Systems (1) Allow sharing of data Control of redundancy Ensure data consistency Improve data standards More control over concurrency

Advantages of Database Systems (2) Better data security Improved data integrity Better backup and recovery procedures Fast development of new applications Better data accessibility

Disadvantages of Database Systems Increased costs Management complexity Maintaining currency Vendor dependence Frequent upgrade/replacement cycles

File Systems and Databases

A Simple Database Everyone Can Do – Flat File

Flat file When data grow, processing may be difficult A dedicated program may create to read the flat file database Read line by line, fields are separated using a separator However, flat file database is subjected to structural, data dependence and data redundancy.

A Conventional File System

File System (1) Contents of each file folder are logically related Manual file systems Served as a data repository for small data collections Cumbersome for large collections Computerized file systems Data processing (DP) specialist converted computer file structure from manual system Wrote software that managed the data Designed the application programs

File System (2) Initially, computer file systems resembled manual systems As number of files increased, file systems evolved Each file used its own application program to store, retrieve, and modify data Each file was owned by individual or department that commissioned its creation

Computerized File Systems

A Simple File System

File System Redux: Spreadsheet Ubiquitous use of personal productivity tools can introduce the same problems as the old file systems Microsoft Excel Widely used by business users Users have become so adept at working with spreadsheets, they tend to use them to complete tasks for which spreadsheets are not appropriate – database substitute

Problems with File System Data Processing Lengthy development times Difficulty of getting quick answers Complex system administration Lack of security and limited data sharing Extensive programming

Contrasting Database and File Systems

Preparing for Your Database Professional Career

Question?

Which is the following businesses require database? An ice-cream store A tuition center A computer hardware and repair store A pharmacy A car spare-part store A florist store A Real estate corporation A clinic A second hand car dealer A furniture store