23 relationship a relationship is a situation that

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2.3 Relationship A relationship is a situation that exist the relation between two databases where one table has foreign key that references the primary key of the other table. Relationship allow the relational data to stored data in different tables. There are various types’ relationship entities: One-to-One A pair of tables that bears one-to-one relationship when single record in the first table is related to only one in the second table and vice-versa. 18 | P a g e DATABASE AND DESIGN
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Fig: Example of one-to-one relationship One-to-Many Relationship A one-to-many relationship exists between a pair of tables when a single record in the first table can be related to one or more records in the second table, but a single record in the second table can be related to only one record in the first table. Fig: one to many Relationship Many -to- Many Many instance of the one entity are related with many instance of another entity. Many –to- One Many instance of the one entity with only one records of another entity. 19 | P a g e DATABASE AND DESIGN
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Data Flow Diagram Symbol Process - External Entity/Input - Data Store in device on File- Data Flow – Schema Diagram A mental codification of experience that includes a particular organized way of perceiving cognitively and responding to a complex situation or set of stimuli. (Merriam-webster.com, 2016) It is the structure behind data organization, it is also known as the visual representation of how different table relationship enable the schema under the rules and mission of the organization for which database is created. In a schema diagram, all the database table are design with a unique column with special features, e.g. primary key, foreign key etc. formats and symbols are universally understood to eliminating the confusion. The table relationship also expressed via as a parents table as a parents table and child table corresponding as a foreign key. Schema have important function because they force the database developer to transpose ideas to paper. This provides an overview of the database, while facilitating future database organization work. 20 | P a g e DATABASE AND DESIGN
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Fig: schema Diagram Database Normalization up to 3NF Normalization Normalization is the process of organizing data in a database. This includes creating tables and establishing relationships between those tables according to rules designed both to protect the data and to make the database more flexible by eliminating redundancy and inconsistent dependency. In a one-word Normalization is the process of breaking down a single big table into many smaller tables with fields. Advantages Smaller Database: Eliminating duplicate data, we can reduce the size of database. Better performance It simplifies the data structure Disadvantages Complex design due to the different table’s relationship.
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