Data Resource ManagementSlide 2Problems with File ProcessingBenefits and Limitations of the Database ApproachLimitations of the Database ApproachDatabase StructuresRelational DatabasesDatabase AccessNormalizationNormal FormsKeysSteps Of NormalizationData Resource ManagementA managerial activity that applies information systems technology and management tools to the task of managing an organization’s data resourcesData Resource ManagementFile ProcessingData are organized, stored and processed in independent files of data recordsDatabase ProcessingData are organized, stored and processed in interrelated files of data recordsFiles are dependent on information in other filesProblems with File ProcessingData duplication or data redundancyLack of data integrationData DependenceEach program is dependent on how the information is stored in the fileIf the zip code changes from 5 bytes to 9 bytes, every program which uses the file must be changedBenefits and Limitations of the Database ApproachBenefitsReduces duplication of dataImproves integrity of dataPrograms are independent of dataComputer programming is simplifiedIncreased accessibility of data to usersLimitations of the Database ApproachIncreased technology difficultyNormalization of fileData ModelingCost of the Database Management SystemIncreased accessibility of data to the users can lead to increased fraud and inappropriate manipulation of dataDatabase StructuresRelationalBecause some files have a one to many relationship while other files have a many to many relationship, hierarchical and network models are not always applicableVery popular todayIs viewed as a table•Rows of the table are the data records•Columns of the table are the fields on the recordsRelational DatabasesEach file in the database needs a key which links the file to the other files in the databaseCan have more than one key in a filePrimary key•Storage SequenceForeign key •Generally used to link to another fileDatabase AccessSequentialAll records are key (usually in sequence by the key)Example: To print the timetable, all records on the class file must be read and printedDirect AccessKey transformation -- the key to a file can be transformed to give the location of the record on diskIndexed - an index consisting of the key to each record and the address of the record can be created. The index is searched and only the one address is read.NormalizationA technique that organizes data attributes (or fields) such that they are grouped to form stable, flexible and adaptive entities.Normal FormsFirst Normal Form (1NF)There are no attributes (fields) that have more than one value for a single instance (record) of the entity.There are no repeating fieldsSecond Normal Form (2NF)1NFThe value of all non-primary key fields are dependent on the full primary key - not just part of itThird Normal Form (3NF)2NFThe values of its non-primary key fields are not dependent on any other non-primary key fieldKeysPrimaryA field whose values identify one and only one record in a tableEvery ACCESS table must have EXACTLY one primary keyForeignA primary key of one table that is included in another tableLinks the records in one database table to another tableSteps Of Normalization1. Remove repeating groups of data fields.2. Remove partial dependencies: If any data fields are dependent upon only part of the primary key defined for your core business transaction, split those fields out into a separate table, using the field(s) upon which they are dependent as the primary key.3. Remove transitive dependencies: If any fields are dependent upon a non-key field, split those fields out into a separate table, using the non-key field as the primary key. 4. Remove any field which can be derived from other field(s) : If any fields can be derived from others, remove from database.5. Check by drawing/comparing to E-R diagram: is this model