Difference between revisions of "Databases"

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==Terminology of relational model==
 
 
A database is an organized collection of data. It is the collection of schemas, tables, queries, reports, views, and other objects. https://en.wikipedia.org/wiki/Database
 
A database is an organized collection of data. It is the collection of schemas, tables, queries, reports, views, and other objects. https://en.wikipedia.org/wiki/Database
  
  
* What is the primary key: '''title_id'''
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* What is the foreign key: '''Pub_id'''
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==[[Database design]]==
* What is the cardinality: '''13'''
 
: <span style="color:#FFFFFF; background:#000000"> select  count(title_id) as 'Cardinality of the «titles» table' from titles; </span>
 
* What is its degree: '''9'''
 
* What is the domain of contract: '''Smallint(6) NOT NULL'''
 
  
* What is the domain of ''country'' in the table ''Publishers'': '''varchar(15) NOT NULL'''
 
  
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==[[MySQL]]==
  
  
==[[MySQL]]==
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==[[PostgreSQL]]==
  
  
 
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Revision as of 22:55, 19 June 2020

A database is an organized collection of data. It is the collection of schemas, tables, queries, reports, views, and other objects. https://en.wikipedia.org/wiki/Database



Database design


MySQL


PostgreSQL