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Chapter 11

Chapter 11. Databases. Chapter Contents. Section A: File and Database Concepts Section B: Data Management Tools Section C: Database Design Section D: SQL Section E: Database Security. File and Database Concepts. Database Basics Database Models. Database Basics.

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Chapter 11

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  1. Chapter 11 Databases

  2. Chapter Contents • Section A: File and Database Concepts • Section B: Data Management Tools • Section C: Database Design • Section D: SQL • Section E: Database Security Chapter 11: Databases

  3. File and Database Concepts • Database Basics • Database Models Chapter 11: Databases

  4. Database Basics • A database is a collection of information • Typically stored as computer files • The tasks associated with creating, maintaining, and accessing the information in databases are referred to as data management, file management, or database management Chapter 11: Databases

  5. Database Basics • Databases can be used in a variety of ways • Collect and store data • Update data • Organize and output data • Distribute data • Find data • Analyze data Chapter 11: Databases

  6. Database Basics • Data mining refers to the process of analyzing existing information in databases to discover previously unknown and potentially useful information, including relationships and patterns • Data warehouse • Predictive analytics Chapter 11: Databases

  7. Database Models • An unstructured file has a unique structure • A structured file uses a uniform format to store data • The underlying structure of a database is referred to as a database model Chapter 11: Databases

  8. Database Models • The simplest model for storing data is a flat file that consists of a single, two-dimensional table of data elements Records can be displayed as rows in a table or as forms. Chapter 11: Databases

  9. Database Models • A field contains the smallest unit of meaningful information • Each field has a unique field name • Variable-length field vs. fixed-length field Chapter 11: Databases

  10. Database Models • A record is a related collection of data fields • The template (blank form) for a record is referred to as a record type • A record that contains data is referred to as a record occurrence Chapter 11: Databases

  11. Database Models • A relationship is an association between data that is stored in different record types • One-to-many • Many-to-many • One-to-one Chapter 11: Databases

  12. Database Models • A hierarchical database arranges record types in a hierarchy Chapter 11: Databases

  13. Database Models • The network database model allows many-to-many relationships in addition to one-to-many relationship Chapter 11: Databases

  14. Database Models • A relational database stores data in a collection of related tables Much more flexible than hierarchical or network models. Chapter 11: Databases

  15. Database Models • A (multi)dimensional database organizes relationships over three or more dimensions Easy to maintain. Data is stored in a structure related to its use. Used primarily for data analysis and decision support systems. Chapter 11: Databases

  16. Database Models • An object (object-oriented) databasestores data as objects, which can be grouped into classes and defined by attributes and methods Chapter 11: Databases

  17. Database Models • An object-relational database is used to describe a variety of technologies that combine object-oriented and relational concepts Chapter 11: Databases

  18. Data Management Tools • Data Management Software • Database Management Systems • Databases and the Web • XML Chapter 11: Databases

  19. Data Management Software Microsoft Word allows you to create a “flat” table of information, such as a mailing list, which you can edit, sort, search, and print. In addition, you can merge data from the table with a template letter to create form letters, mailing labels, and envelopes. Chapter 11: Databases

  20. Data Management Software MS Excel Chapter 11: Databases

  21. Data Management Software • It is possible to enter data as ASCII text file • Custom data management software • Data dependence vs. data independence Chapter 11: Databases

  22. Database Management Systems • Software packages designed to manage data stored in a database • XML DBMS (primarily for use on the Web) • OODBMS (object-oriented DBMS) • RDBMS (Relational DDMS - often include tools to deal with XML and object-oriented data) Chapter 11: Databases

  23. Database Management Systems An entry-level DBMS, like Microsoft Access, usually includes all the tools you need to manipulate data in a database. Chapter 11: Databases

  24. Database Management Systems • Database client software allows a remote computer or network workstation to access data in a remote database (database server) Chapter 11: Databases

  25. Database Management Systems • Multiple users can interact with the same database Chapter 11: Databases

  26. Databases and the Web • The Web provides opportunities and challenges for accessing databases • Static Web publishing (read-only snapshot of data) • Dynamic Web publishing (script-driven, on-the-fly view of data) • Server-side program Chapter 11: Databases

  27. Databases and the Web Chapter 11: Databases

  28. Databases and the Web • Forms can collect data for database update,as well as specifications for a query • XForms: an alternative to HTML forms Chapter 11: Databases

  29. Databases and the Web • Several tools are available to help create server-side programs ASP: Active Server Pages (Microsoft) CGI: Common Gateway Interface (standard) PHP: Hypertext Preprocessor Chapter 11: Databases

  30. XML Documents • Markup language allows field tags, data, and tables to be incorporated into a Web document Chapter 11: Databases

  31. XML Documents • Used to specify a standard structure of fields and records • Data in an XML document is searchable via XML query engines (XPath, XQuery) • XML is portable, but not optimized for many common database operations • Consider storing data in a relational database, managing it with RDBMS software, and generating XML documents for exchanging data over the Web Chapter 11: Databases

  32. Database Design • Defining Fields • Normalization • Organizing Records • Designing the Interface • Designing Report Templates • Loading Data Chapter 11: Databases

  33. Defining Fields • The term database structure refers to the arrangement of fields, tables, and relationships in a database • Example: Storing last names and first names in separate fields • Use a primary key field to make each record unique (e.g., your student id #) • Use appropriate data types for each field (e.g., store numbers as numbers, not text) Chapter 11: Databases

  34. Defining Field Some Basic Data Types: Chapter 11: Databases

  35. Defining Fields • A computed (calculated, derived) field is a calculation that a DBMS performs during processing and stores temporarily • Uppercase and lowercase are not always treated the same • Case sensitive database • Field formats show what the data is supposed to look like when it’s entered • Field validation rules are used to filter data Chapter 11: Databases

  36. Normalization • Process that helps save storage space and increase processing efficiency • Reduces data redundancy Notice that in this example, there is no need to carry complete customer info in each record for every order. Chapter 11: Databases

  37. Organizing Records • Records can be organized in different ways, depending on use • Sorting • A table’s sort order refers to the order in which records are stored in the database • The sort key is the field that is used to determine the sort order • Indexing • Refers to an index number for the record for each sort key • Similar to the index in a book (“where do I find….?”) Chapter 11: Databases

  38. Organizing Records When indexed by date, the index file contains a list of keys and the record number (R#) that contains more information about the album released on that date. Chapter 11: Databases

  39. Designing the Interface • Arrange fields in a logical order • Provide visual clues to the entry areas • Entry areas should appear in a consistent position relative to their labels • Provide a quick way to move through the fields in order Chapter 11: Databases

  40. Designing the Interface • Use scrolling or create multiple screens, if necessary • Provide buttons or other easy-to-use controls for navigating through records • Supply on-screen instructions Chapter 11: Databases

  41. Designing the Interface Chapter 11: Databases

  42. Designing Report Templates • Report generators are used to specify the content and format for a database report • A report template contains the outline or general specifications for a report Chapter 11: Databases

  43. SQL • SQL Basics • Adding Records • Searching for Information • Updating Fields • Joining Tables Chapter 11: Databases

  44. SQL Basics • Intermediary between the database client software and the database itself • Query language • SQL: Structured Query Language Chapter 11: Databases

  45. SQL Basics Some Basic SQL Commands: Chapter 11: Databases

  46. Adding Records Chapter 11: Databases

  47. Searching for Information SELECT AlbumTitle, AlbumCover FROM Albums WHERE ArtistName = ‘Jefferson Airplane’ • The AND, OR, and NOT Boolean operators are used to perform complex SQL searches • The use of parentheses indicates the part of the query to perform first (specifies precedence of operations) Chapter 11: Databases

  48. Updating Fields UPDATE Albums SET InStock = InStock – 1 WHERE AlbumTitle = ‘G.I. Blues’ • Global updates change the data in more than one record at a time • Works only for records with similar characteristics Chapter 11: Databases

  49. Joining Tables • Joining tables in SQL allows you to create relationships between tables Chapter 11: Databases

  50. Joining Tables SELECT Albums.AlbumTitle, Albums.AlbumCover, Albums.DiscountPrice, Tracks.TrackTitle FROM Albums JOIN Tracks on Albums.Cat# = Tracks.Cat# WHERE Album.Cat# = ‘LPM-2256’ Chapter 11: Databases

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