Contains metadata data about data System catalog Contains metadata Detailed

Contains metadata data about data system catalog

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Contains metadata: data about data System catalog Contains metadata Detailed system data dictionary that describes all objects within the database
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NIK UiTM 20
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21 NIK UiTM Homonyms & Synonyms Homonyms Similar sounding words with different meanings. Identical spelled words with different meanings. In database – the use of the same attribute name to label different attributes E.g :C_name in Customer table and C_name in Colsultant Synonyms Different names to describe the same attribute. In database – same attribute occurs in different table with different names. E.g: Auto and car same meaning
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Relationships within the Relational Database NIK UiTM 22 1:M relationship Relational modeling ideal Should be the norm in any relational database design 1:1 relationship Should be rare in any relational database design M:N relationships Cannot be implemented as such in the relational model M:N relationships can be changed into 1:M relationships
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The 1:M Relationship NIK UiTM 23 Relational database norm. Found in any database environment Make sure that the primary key of the one is includes as a foreign key in the table of the many.
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NIK UiTM 24
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The 1:1 Relationship NIK UiTM 25 One entity related to only one other entity, and vice versa Sometimes means that entity components were not defined properly Could indicate that two entities actually belong in the same table As rare as 1:1 relationships should be, certain conditions absolutely require their use
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NIK UiTM 26
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The M:N Relationship NIK UiTM 27 M:N relationship can be implemented logically but not in RDMSs because :- The tables create many redundancies Relational operations become very complex and are likely to lead system efficiency errors and output errors. Can be implemented by breaking it up to produce a set of 1:M relationships by creating a composite entity or bridge entity.
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NIK UiTM 28
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29 The M:N Relationship (continued) NIK UiTM
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30 NIK UiTM Composite entity
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NIK UiTM 31 Composite entity
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32 NIK UiTM
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33 NIK UiTM
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