L4+-+Datamodeling

L4+-+Datamodeling - ACCOUNTING INFORMATION SYSTEM...

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ACCOUNTING  INFORMATION SYSTEM DATAMODELLING
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DATABASE What is a database?   A large collection of  related data  that  are typically stored in computerized,  linked files and manipulated by  specialized software packages called  database management systems  (DBMSs)
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DATABASE   The Data Hierarchy Bit   Character   Data Field   Record   File   Database   Bit : the lowest level of information   Character : eight bits create a byte of data that can  represent a single character Data field:  several characters form a data field, e.g. an  account balance; also called “attribute” or “column” a database  record  stores all the information about one file  entity, e.g. one employee in a payroll file a set of common record forms a  file  or a  table Master files: typically store permanent information  Transaction files: typically store transient information  several tables and related files create a complete  database
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Record Structures The specific data fields in each record of a database table  are part of what is called the  record structure   Record Keys  Primary record key: The data field in each record that uniquely distinguishes  one record from another in a database table  Secondary record key  The data field in each record that can be used to search  records for specific information, but is not unique across  records  Foreign keys:  The data field that can be used to reference one or more  records in other tables DATABASE
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DATABASE DESIGN  Data Modeling A data model is an abstract representation of  the contents of a database An important aspect of database design. Conceptual  Design Systems  Analysis Physical Design Implementation  Maintenance Data  Modeling  Occurs Here Data  Modeling  Used Here
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ENTITY-RELATIONSHIP MODELS Represent a business in a graphical  approach using three terms to describe a  company’s information Entities (nouns)  are the objects found in the  company (e.g., invoices, purchase orders, etc.) Relationships  are the way in which the distinct  entities interact or are related to one another Attributes (adjectives)  describe the entities and  relationships Entities and relationships are represented  by diagrams
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Entity-relationship diagram. Customer
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This note was uploaded on 10/14/2010 for the course ACTG 3P97 taught by Professor Xiazhang during the Fall '10 term at Brock University.

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L4+-+Datamodeling - ACCOUNTING INFORMATION SYSTEM...

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