Recent questions tagged Relational

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relational database - What is the difference between theta join and inner join?

theta join and inner join look identical to me: they are Cartesian product followed by an arbitrary selection. Or am ... join and an inner join. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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relational division - MySQL Select ID's which occur on different rows with multiple specific values for a column

I'm trying to select items from an associative table that have satisfy two or more values of the same field, ... . Thank you for your help. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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relational - SQL selecting rows where one column's value is common across another criteria column

I have a cross reference table that looks like this: id document_id subject_id 1 8 21 2 5 17 3 5 76 4 7 88 ... way to query for this in SQL? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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relational database - retrieve correct data from my schemas

I would like to retrieve the Names of teachers who teach more than 1 course I am really stuck on how to ... i any specific database language)? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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relational - Database schema-related problem

I have a kind of theoretical question about databases. To make it more concrete I have thought up an example ... better solution to my problem? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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