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Databases Nanda Ganesan, Ph.D. Objective Q1: What is the purpose of a database? Q2: What is a database? Q3: What is a database management system (DBMS)? Q4: How do database applications make databases more useful? Q5: What is a NoSQL DBMS? Copyright © 2015 Pearson Education, Inc. Q3: What Is a Database Management System (DBMS)? • Program used to create, process, and administer a database • Licensed from vendors such as IBM, Microsoft, Oracle, and others • DB2 from IBM, Access and SQL Server from Microsoft, Oracle Database from Oracle Corporation • MySQL - open source, license-free for most applications Copyright © 2015 Pearson Education, Inc. Database Definition • Database Management System (DBMS) – Access, Oracle etc. • Database Application Systems – Student enrollment management system, enrollment management system Data and Information • Data – Unprocessed • Information – Processed Q1: What Is the Purpose of a Database? • Organize and keep track of things • Keep track of multiple themes • General rule: Single theme - store in a spreadsheet Multiple themes - use a database Copyright © 2015 Pearson Education, Inc. A List of Student Grades Presented in a Spreadsheet – Single Theme Copyright © 2015 Pearson Education, Inc. Student Data Shown in a Form, from a Database Copyright © 2015 Pearson Education, Inc. Data Processing • Data Integrity – Database is as valid as the correctness of the information stored and processed – GIGO Good Information Characteristics • • • • • • • Accurate Verifiable Timely Organized Accessible Useful Cost-effective Data Hierarchy Field1 (Primary) Record 1 File 1.1 Database Application 1 Record 2 File 1.2 Database Server Database Application 2 Field 2 File 2.1 Q2: What Is a Database? Copyright © 2015 Pearson Education, Inc. Hierarchy of Data Elements Copyright © 2015 Pearson Education, Inc. Components of a Database Copyright © 2015 Pearson Education, Inc. Example of Relationships Among Rows Copyright © 2015 Pearson Education, Inc. Sample Metadata (in Access) Database Components File Characteristics Data Types Text Numeric Date Memo Object AutoNumb er Yes/No Attachment Currency Hyperlink Data Dictionary Maintaining Data • • • • Add Modify Delete Validate Data Validation Alphabetic/Nume ric Check Range check Completeness check Check digit Consistency check Evolution of Database Management Systems • • • • File processing system Hierarchical database systems Relational database systems Object oriented database systems File Processing and Database System Advantages of Database Systems • • • • Reduced data redundancy Improved data integrity Efficiently shared data Relatively simple development Examples of Database Management Systems Q4: How Do Database Applications Make Databases More Useful? • Database application – Collection of forms, reports, queries and application programs serves as intermediary between users and database data. • Application programs – Provide security, maintain data Copyright © 2015 Pearsonand Education, Inc. consistency, handle special cases. Specific Purposes of Four Elements of a Database Application Copyright © 2015 Pearson Education, Inc. Traditional Forms, Queries, Reports, and Applications Copyright © 2015 Pearson Education, Inc. Browser Forms, Reports, Queries, and Applications Copyright © 2015 Pearson Education, Inc. Browser Report for SharePoint Site Copyright © 2015 Pearson Education, Inc. Access Database Components • • • • • • • Tables Queries Forms Reports Macros Modules Visual Programming (Visual Basic) Relational Database • The entity-relationship model • Entities (objects) – Students, classes etc. • Relationships – Enrollment (Student to Classes) Types of Relationships • • • • One-to-one One-to-Many Many-to-Many A design example – Creating tables to capture a database Querying the Tables and the Database • Query by Example • Query Language – SQL is the most popular query language Processing the Database • Structured Query Language - SQL (see-quell) – International standard – Used by most popular DBMS INSERT INTO Student ([Student Number], [Student Name], HW1, HW2, MidTerm) VALUES (1000, ‘Franklin, Benjamin’, 90, 95, 100); Copyright © 2015 Pearson Education, Inc. Sample SQL Statement Administering the Database • Used to set up a security system involving user accounts, passwords, permissions, and limits for processing. • Permissions can be limited in very specific ways. • Backing up database data, adding structures to improve performance of database applications, removing unwanted data. Copyright © 2015 Pearson Education, Inc. Other Database Models • Object oriented database model – Contains code and data • Multidimensional database – In comparison, relational database is a two-dimensional database • Web database – Back end database to a front-end web server Database Personnel • Database analyst • Database administrators • Database users Experiencing MIS InClass Exercise 5: How Much Is a Database Worth? • Data has resale value. • Data on everything customers do. • Use to target customer for offerings they care about, avoid those they don’t. • Costly and difficult to replace data collected over many years. Copyright © 2015 Pearson Education, Inc. Other Database Terms • Data warehouse • Data mining Big Data • The processing of large amount of data – FaceBook – Supermarkets Q5: What Is a NoSQL DBMS? NOSQL DBMS (NotRelational DBMS • Supports very high transaction rates • Relatively simple data structures • Replicated on many servers in the cloud • Examples • Dynamo (Amazon) • Bigtable (Google) • Cassandra (Facebook) Copyright © 2015 Pearson Education, Inc. Will NoSQL Replace Relational DBMS Products? •Conversion very expensive and disruptive. •Very technical, limited to those with a deep background in computer science. •Requires years of training to use. •Organization may choose NoSQL products for specialized applications. Copyright © 2015 Pearson Education, Inc. Guide: No, Thanks, I’ll Use a Spreadsheet • Story of the failed database project • Database works but doesn’t meet the requirements of this salesperson. • Cause of database failures usually either incompetent database developers or underfunding. • Causes of systems development failure--poor communication between users and systems developers, lack of clear requirements, and inability to manage requirements. Copyright © 2015 Pearson Education, Inc. Guide: No, Thanks, I’ll Use a Spreadsheet (cont'd) • Databases take time to build. • Complicated to operate. • Need IS people to create and keep them running. • Salesman doesn’t want to share data. • Spreadsheets sometimes better option, especially if data needs are simple. Copyright © 2015 Pearson Education, Inc. Case Study 5: Fail Away with Dynamo, Bigtable, and Cassandra • Current relational DBMS products not designed for large, multi-server systems • NoSQL databases – Dynamo (elastic), Bigtable (elastic), Cassandra (used by Facebook, Twitter, Digg, Reddit) • Amazon: Dynamo • Google: Bigtable processes petabytes of data on hundreds of thousands of servers Copyright © 2015 Pearson Education, Inc. Case Study 5: Fail Away with Dynamo, Bigtable, and Cassandra • Current relational DBMS products not designed for large, multi-server systems • NoSQL databases – Dynamo (elastic), Bigtable (elastic), Cassandra (used by Facebook, Twitter, Digg, Reddit) • Amazon: Dynamo • Google: Bigtable processes petabytes of data on hundreds of thousands of servers Copyright © 2015 Pearson Education, Inc. END