A diagram that represents entities and their relationships A student entity

A diagram that represents entities and their

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A diagram that represents entities and their relationships A “student” entity represents all students in th e system Individual students will be instances of the “student” entity An entity must have multiple instances Primary Key a unique attribute used to identify a single instance of an entity o Compound Primary Key a unique combination of attributes used to identify a single instance of an entity o Often an entity has many instances o Therefore, there is a need to uniquely identify each instance (record in the table) o Primary key is a unique identifier for each record
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Svac 5 Relationship natural business association that exists between one or more entities o Implicitly bi-directional o A verb phrase is used to name relationships (i.e. submit) o A 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 o Central repository of shared data o Data is managed by the DBMS o Stored in a standardized, convenient form o Advantages: 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 o Risks/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 o Digital once a good can be digitalized, it can be replicated with perfect quality, distributed with minimal costs, and results can be easily measured
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Svac 6 o Exponential IT has been exponentially improving over the past several decades, meaning the rate of growth itself is improving. o Combinatorial IT can be combined in many different ways to successively develop more innovative products, meaning layering and leveraging other technology advancements. Information Processing Cycle o Input (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 o Data o Hardware o Software o Media o Procedures o People How it helps o Let’s us gather large amounts of data quickly o Allow for storage and organization of large amounts of data o Data manipulations are performed quickly o
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