Database Introduction PDF

Introduction to Computer Engineering 07–DATABASE Perihan Pehlivanoğlu Dr. Biruni University Computer Engineering Department 1  Database A collection of data that is multidimensional in the sense that internal links betwee...

Introduction to Computer Engineering 07–DATABASE Perihan Pehlivanoğlu Dr. Biruni University Computer Engineering Department 1  Database A collection of data that is multidimensional in the sense that internal links between its entries make the information accessible from a variety of perspectives. 9-2  Text File-LOG style 0-3  Text File-Structured Data Store 0-4  Text File-Structured Data Store 0-5  Largest Databases in the World Library of Congress 130 million items (books, photographs, maps, etc) 29 million books 10,000 new items added each day 530 miles of shelves 5 million digital documents 20 terabytes of text data AMAZON 59 million active customers More than 42 terabytes of data 6  Youtube Given: 650,000 videos per day X 30 days per month = 19,500,000 videos per month; 10 terabyte = 10,048,576 megabytes. If we assume that each video has a size of 1MB, YouTube would expect to grow 18.6 terabytes next month. Similarly, if we assume that each video has a size of 10MB, YouTube would expect to grow 186 terabytes next month. 7  AT&T United States' oldest telecommunications company AT&T maintains one of the world's largest databases. 323 terabytes of information 1.9 trillion phone call records 8  You can... Add a line to any row (INSERT) Delete a line (DELETE) Sort the table (INDEX or SQL) Find any item (SELECT SQL) in more EFFICIENT way 0-9  Figure 9.1 A file versus a database organization 9-10  Figure 9.1 A file versus a database organization 9-11  Figure 9.2 The conceptual layers of a database implementation 9-12  Database Management Systems Database Management System (DBMS): A software layer that manipulates a database in response to requests from applications https://www.youtube.com/watch?v=JZfeeyP-tCM 9-13  Database Management Systems Distributed Database: A database stored on multiple machines DBMS will mask this organizational detail from its users Data independence: The ability to change the organization of a database without changing the application software that uses it 9-14  Data independence IN writing programs in C (or C++) if you change a variable type you need to recompile it. However if source codes are not with you, this is a problem) Therefore C++ is data dependent. 15  Relational Database Model Relation: A rectangular table Attribute: A column in the table Tuple: A row in the table 9-16  Relational Database 0-17  Relational Database 0-18  Relational Database 0-19  Relational Database 0-20  Relational Database 0-21  Relational Database 0-22  Relational Database 0-23  Structured Query Language (SQL) Operations to manipulate tuples insert update delete select 9-24  SQL Examples 9-25  SQL Examples SELECT EmplId, Dept FROM Assignment, Job WHERE Assignment.JobId = Job.JobId AND Assignment.TermData = '*'; Main focus is this. % 80 of SQL Statements Uses This.. 9-26  SQL Examples 9-27  SQL Examples (continued) INSERT INTO Employee VALUES ('43212', 'Sue A. Burt', '33 Fair St.', '444661111'); DELETE FROM Employee WHERE Name = 'G. Jerry Smith'; UPDATE Employee SET Address = '1812 Napoleon Ave.' WHERE Name = 'Joe E. Baker'; 9-28  SQL Examples 9-29  SQL Examples 9-30  SQL Examples 9-31  Search in a Indexed(ordered) list 0-32  Use of Indexes 0-33  Indexed Files Index: A list of key values and the location of their associated records. An index for a file contains a list of the keys stored in the file along with entries indicating where the record containing each key is stored. 9-34 Figure 9.17 Opening an indexed file 9-35  Hashing Each record has a key field The storage space is divided into buckets A hash function computes a bucket number for each key value Each record is stored in the bucket corresponding to the hash of its key 9-36  Figure 9.18 Hashing the key field value 25X3Z to one of 41 buckets 9-37  Figure 9.18 Hashing the key field value 25X3Z to one of 41 buckets 9-38  Data Mining Data Mining: The area of computer science that deals with discovering patterns in collections of data Data warehouse: A static data collection to be mined Data cube: Data presented from many perspectives to enable mining 9-39  End of Chapter Copyright © 2015 Pearson Education, Inc.