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A diagram that represents entities and their relationships A “student” entity represents all students in the system Individual students will be instances of the “student” entityAn entity must have multiple instances Primary Key–a unique attribute used to identify a single instance of an entity oCompound Primary Key –a unique combination of attributes used to identify a single instance of an entity oOften an entity has many instances oTherefore, there is a need to uniquely identify each instance (record in the table) oPrimary key is a unique identifier for each record
Svac 5 Relationship–natural business association that exists between one or more entities oImplicitly bi-directional oA verb phrase is used to name relationships (i.e. submit) oA relationship means that instances of one entity can be related to instances of another entity How do you do that? Through foreign key, which is the join field Foreign key–primary key of one entity that is duplicated in another entity to identify instances of a relationship Associative Entities The Database Approach oCentral repository of shared data oData is managed by the DBMS oStored in a standardized, convenient form oAdvantages: Program-data independence Minimal data redundancy Improved data consistency Improved data sharing Increased productivity of application development Enforcement of standards Improved data quality Improved data accessibility and responsiveness Reduced program maintenance Improved decision support oRisks/Drawbacks of DBMS Main costs: High initial investment Additional hardware Overhead Training DBMS may be unnecessary Application is simple, well-defined, and not expected to change Data in application is not shared with other applications Stringent real-time requirements Write access to data by multiple users is not needed Lecture V –Information Systems for Business Three Pillars of IT Growth oDigital –once a good can be digitalized, it can be replicated with perfect quality, distributed with minimal costs, and results can be easily measured
Svac 6 oExponential –IT has been exponentially improving over the past several decades, meaning the rate of growth itself is improving. oCombinatorial –IT can be combined in many different ways to successively develop more innovative products, meaning layering and leveraging other technology advancements. Information Processing Cycle oInput (Collect and Convert Data into usable form) Process (manipulation and transformation of data into information) (Storage (holds data and information so that it can be retrieved later) Output (presented information in a form that can be useable Types of Components in IS oData oHardware oSoftware oMedia oProcedures oPeople How it helps oLet’s us gather large amounts of data quicklyoAllow for storage and organization of large amounts of data oData manipulations are performed quickly o