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| − | ==Terminology of relational model==
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| − | 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
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| − | * What is the primary key: '''title_id'''
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| − | * What is the foreign key: '''Pub_id'''
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| − | * What is the cardinality: '''13'''
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| − | : <span style="color:#FFFFFF; background:#000000"> select count(title_id) as 'Cardinality of the «titles» table' from titles; </span>
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| − | * What is its degree: '''9'''
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| − | * What is the domain of contract: '''Smallint(6) NOT NULL'''
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| − | * What is the domain of ''country'' in the table ''Publishers'': '''varchar(15) NOT NULL'''
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| − | ==[[MySQL]]==
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| − | <br />
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