1. Data and itsrepresentationRuhulla Abdul1st year IFF studentFinancial University under the Government ofthe Russian FederationMoscow2014 2. Content Database DBMS Database model Relational database Ensuring Data Integrity Understanding data and data-gathering Different parts of a database The database planning process Post-relational database 3. What is a database?A database is a storage space for content / information (data)Data is factual information about objects and concepts, such as: measurements statisticsYou can find it in: filing cabinets spreadsheets folders ledgers lists colleagues memories piles of papers on your desk 4. Database System Database:A collection of related data. Data:Database System:DBMS + DatabaseKnown facts that can be recorded and have animplicit meaning. Database Management System (DBMS):A software package/system to facilitate theDefine, Construct, Manipulate and Share functions of acomputerized database. 5. DBMS Software package for defining and managing a database. Examples: Proprietary: MS Access, MS SQL Server, DB2, Oracle, Sybase Open source: MySql, PostgreSQL 6. DBMS Advantages Program-data independence Minimal data redundancy Improved data consistency & quality Access control Transaction control Improved accessibility & data sharing Increased productivity of application development Enforced standards 7. Typical DBMS Functionality Define a particular database in terms of its data types, structures,and constraints Construct or Load the initial database contents on a secondarystorage medium Manipulate the database: Retrieval: Querying, generating reports Modification: Insertions, deletions and updates to its content Accessing the database through Web applications Share a database allows multiple users and programs to access thedatabase simultaneously 8. Database modelA database model is a type of data model that determines the logical structure of a database andfundamentally determines in which manner data can be stored, organized, and manipulated.Common logical data models for databases include: Hierarchical database model Network model Relational model Entityrelationship model Enhanced entityrelationship model Object model Document model Entityattributevalue model Star schemaAn object-relational database combines the two related structures.Physical data models include: Inverted index Flat fileOther models include: Associative, Multidimensional, Multivalue l, Semantic, XML database Namedgraph, Triplestore 9. Common types of data modelsA database model is a specification describing how a database is structured and used.Several such models have been suggested. Common models include: Flat model - This may not strictly qualify as a data model. The flat (or table) model consists of asingle, two-dimensional array of data elements, where all members of a given column areassumed to be similar values, and all members of a row are assumed to be related to oneanother. Hierarchical model - In this model data is organized into a tree-like structure, implying a singleupward link in each record to describe the nesting, and a sort field to keep the records in aparticular order in each same-level list. Network model - This model organizes data using two fundamental constructs, called records andsets. Records contain fields, and sets define one-to-many relationships between records: oneowner, many members. Relational model - is a database model based on first-order predicate logic. Its core idea is todescribe a database as a collection of predicates over a finite set of predicate variables,describing constraints on the possible values and combinations of values. Object-relational model - Similar to a relational database model, but objects, classes andinheritance are directly supported in database schemas and in the query language. Star schema - The simplest style of data warehouse schema. The star schema consists of a few"fact tables" (possibly only one, justifying the name) referencing any number of "dimension tables".The star schema is considered an important special case of the snowflake schema. 10. Types of data modelFlat modelHierarchical modelNetwork modelRelational modelObject-relational model Star schema 11. Relational databaseA relational database is a collection of data items organized as a set offormally-described tables from which data can be accessed or reassembledin many different ways without having to reorganize the database tables. It isthe most popular example of a database model, which uses a table-basedformat.The relational database was invented by E. F. Codd at IBM in 1970.The standard user and application program interface to a relational databaseis the structured query language (SQL). SQL statements are used both forinteractive queries for information from a relational database and forgathering data for reports.In addition to being relatively easy to create and access, a relationaldatabase has the important advantage of being easy to extend. After theoriginal database creation, a new data category can be added withoutrequiring that all existing applications be modified.SQL statements are used to retrieve and update data in a database. 12. Structure of relational modelA relational database is a set of tables containing data fitted intopredefined categories. Each table (which is sometimes calleda relation) contains one or more data categories in columns.Each row contains a unique instance of data for the categoriesdefined by the columns. For example, a typical business orderentry database would include a table that described a customerwith columns for name, address, phone number, and so forth.Another table would describe an order: product, customer, date,sales price, and so forth.The Employees table illustrates some ofthese relational database concepts. Ithas five columns and six rows, with eachrow representing a different employee. 13. Structure of relational modelThe primary key for this table would generally be the employee number because each one isguaranteed to be different. (A number is also more efficient than a string for makingcomparisons.) It would also be possible to use First_Name and Last_Name because thecombination of the two also identifies just one row in our sample database. Using the last namealone would not work because there are two employees with the last name of "Washington." Inthis particular case the first names are all different, so one could conceivably use that column asa primary key, but it is best to avoid using a column where duplicates could occur. If ElizabethJones gets a job at this company and the primary key is First_Name, the RDBMS will not allow hername to be added (if it has been specified that no duplicates are permitted). Because there isalready an Elizabeth in the table, adding a second one would make the primary key useless as away of identifying just one row. Note that although using First_Name and Last_Name is a uniquecomposite key for this example, it might not be unique in a larger database. Note also that theEmployees table assumes that there can be only one car per employee. 14. Databases everywhereBecause of the versatility of databases, we find them powering all sortsof projects: A web site that is capturing registered users A client tracking application for social service organisations A medical record system for a health care facility Your personal address book in your e-mail client A collection of word processed documents A system that issues airline reservations 15. Ensuring Data IntegrityInformation first - Database second 16. Understanding data and data-gathering 17. Different parts of a databaseFieldsRecordsQueriesReports 18. Fields Database storage units Generic elements of content 19. RecordsA simple table showing fields (columns) and records(rows):And as part of an MS Access database table: 20. Queries Queries are the information retrieval requests you make to thedatabase Your queries are all about the information you are trying to gather 21. Reports If the query is a question......then the report is its answer Reports can be tailored to the needs of the data-user, making theinformation they extract much more useful 22. The database planning processWhat kind of database are you working on? Information and referral database Contact/client database Donation database (donorbase) Other 23. Information and referral databases Store information about service providers Track and match requests for referral Use a simple design Need to be maintained with up-to-date and complete information 24. Contact/client databases Store contact information for client base Sortable by criteria like: Client interests Services provided Subscription expiry dates Last contacted date 25. Donation databases (donorbases) Generate reports of donations Order or sort donors according to different conditions Record the various donation details of each donor Create and sort lists of potential and current donors Print letters, labels and reports 26. Post-relational databaseThe relational model, first proposed in 1970 by Edgar F. Codd, departed from thistradition by insisting that applications should search for data by content, rather than byfollowing links. The relational model employs sets of ledger-style tables, each used for adifferent type of entity. Only in the mid-1980s did computing hardware become powerfulenough to allow the wide deployment of relational systems (DBMSs plus applications). Bythe early 1990s, however, relational systems dominated in all large-scale data processingapplications, and as of 2014 they remain dominant except in niche areas. The dominantdatabase language, standardised SQL for the relational model, has influenceddatabase languages for other data models. Object databases were developed in the 1980s to overcome the inconvenienceof object-relational impedance mismatch, which led to the coining of the term "post-relational"and also the development of hybrid object-relational databases. The next generation of post-relational databases in the late 2000s became knownas NoSQL databases, introducing fast key-value stores and document-orienteddatabases. A competing "next generation" known as NewSQL databases attemptednew implementations that retained the relational/SQL model while aiming to matchthe high performance of NoSQL compared to commercially available relationalDBMSs. 27. Questions1) What is a database? Give an example of everyday life database2) Use the table below to break each content type into fields. Refer to the list ofexample fields for suggestions3) What is DBMS. Why is it so popular?4) Tell about common types of data models or Draw them5) Relational Database what is it? Why it is so popular?6) Why we use SQL language in relational database?7) Structure of Relational Database8) List part of database. Describe them9) What kind of databases do you know?10) What is Post-relation database?11) Difference between Relation and post-relation database 28. References http://fakit.narod.ru/uch2003/p4_6_2_3.html http://habrahabr.ru/post/152477/ http://citforum.ru/seminars/cbd99/ardent_1.shtml http://en.wikipedia.org/wiki/Database https://en.wikipedia.org/wiki/Relational_model http://www.webopedia.com/TERM/D/database.html http://www.databasejournal.com/ http://en.wikipedia.org/wiki/Database_model