Database management systems
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This document discusses database management systems and their components. It describes how a database stores and organizes related data using tables made of records containing fields. Relational databases relate tables through common fields to better organize large amounts of data. The document outlines how to work with databases, including creating tables, entering and viewing data, sorting, querying, and generating reports from the stored information.
Database management systems
- 1. McGraw-Hill Technology Education McGraw-Hill Technology Education Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved. Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
- 2. Chapter 11A Database Management Systems McGraw-Hill Technology Education Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
- 3. Database Management Systems • • • • 11A-3 Database management system (DBMS) Store large collections of data Organize the data Becomes a data storage system
- 4. The Database • Stores a collection of related items • Collection is arranged in a structure – Organizes and describes the data • Often includes helper documents • Two different types 11A-4
- 6. The Database • Fields – Hold an individual piece of data – Are named descriptively – Often called a column – Phone book examples • Name, address, e-mail, phone number – Fields may contain no data 11A-6
- 7. The Database • Records – One full set of fields – Often called a row – Phone book example • Smith, Joe, 123 Some Street, 412-555-7777 – Databases may have unlimited rows 11A-7
- 8. The Database • Tables – One complete collection of records – Databases may have thousands of tables 11A-8
- 9. Database Helper Documents • Forms – Present one record to the user – Often used to change or view data 11A-9
- 10. Database Helper Documents • Reports – Produce printed results from the database – Includes tools to summarize data 11A-10
- 11. Flat-file Databases • Typically has only one table – If multiple, each has a separate file • Useful for simple data storage needs • Hard to manage large data needs • Can waste disk space 11A-11
- 12. Relational Databases • Made of two or more tables • Tables are related by a common field – Called a relationship or join – Can help organize data • Most common form of database • Maintaining data is easier than flat-file • No wasted disk space 11A-12
- 14. The DBMS • Programs that control the database • Allows – Entering data – Querying data – Printing reports • Supports thousands of users • Includes tools to protect the data 11A-14
- 15. Working with a Database • Creating tables – List the necessary fields – Steps to define a field • Descriptively name the field • Specify the field type • Determine the field size 11A-15
- 16. Working with a Database • Field types – Describes the type of data stored – Most DBMS use the same types • • • • • • • 11A-16 Text fields store letters and numbers Numeric field store numbers Date and time field Logical field stores yes or no Binary field stores images or sounds Counter field generates sequential numbers Memo fields store large amounts of data
- 17. Working with a Database • Entering data into a table – Users type data into a field – Data must be entered accurately • Constraints help to verify data – Forms are typically used for data entry 11A-17
- 18. Working with a Database • Viewing records – Datasheet view shows all records – Filters can limit the records shown • Display only records matching a criteria – Forms allow viewing one record 11A-18
- 19. Working with a Database • Sorting records – Order records based on a field – Multiple sub sorts resolve ‘ties’ – Several types of sorts • • • • • 11A-19 Alphabetic Numeric Chronological Ascending Descending
- 20. Working with a Database • Querying a database – Statement that describes desired data – List of fields can be modified – Uses of querying • Find data • Calculate values per record • Delete records – Most important DBMS skill 11A-20
- 21. Working with a Database • Query languages – All DBMS use a query language • Most DBMS modify the language – Structured Query Language (SQL) • Most common query language – xBase • Query language for dBase systems – Query by example (QBE) • Interface to SQL or xBase • Interactive query design 11A-21
- 22. Query Examples • SQL Select FirstName, LastName, Phone From tblPhoneNumbers Where LastName=“Norton”; • xBase Use tblPhoneNumbers List FirstName, LastName, Phone For LastName=“Norton” 11A-22
- 23. Working with a Database • Generating reports – Printed information extracted from a database – Can calculate data • Calculate data per row • Calculate for entire table – Pictures and formatting can be included 11A-23
- 24. Chapter 11A End of Chapter McGraw-Hill Technology Education Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
Editor's Notes
- #4: Discussion point Ask your student if anyone knows why sorting by zip code is important. Hopefully, someone knows that the post office provides a discount on presorted mail.
- #5: Teaching tip Figure 11A.2 on page 423 describes the database structure
- #10: Teaching tip Figure 11A.3 on page 423 provides examples of forms and reports.
- #12: Teaching tip Start your students thinking about real databases, with millions of records. Using PA instead of Pennsylvania saves 10 bytes per record. In a database with 1 million records, this saves 10,000,000 bytes. This is roughly equal to a stack of 10 floppy disks
- #13: Teaching tip To demonstrate the power of relationships, setup a flat file database with music, artists, CD and year released. Demonstrate how difficult and wasteful it is to store several songs by the same artist and CD. Be sure to make several typing mistakes. Then build the same structure relationally. Create music, artist and CD tables. Join the artist and CD to the music table. Now show how easy it is to add songs from the same CD. While creating this database, it helps to use music the students know.
- #15: Teaching tip Protecting databases is similar to network administration, covered in chapter 9. Access to read and change data is limited to a list of allowed users.
- #17: Teaching tip Dates are stored sequentially in a database. 0 is January 1, 1970 at midnight. 1 is one millisecond after midnight on January 1, 1970. Each date represents the number of milliseconds from January 1, 1970.
- #20: Teaching tip Using a DBMS, demonstrate the power of sorting for the class.
- #21: Teaching tip Page 432 and 433 show examples of the different querying languages.