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00-sql-introduction.md

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Records may also contain keys that refer to records in other tables,
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which enables us to combine information from two or more sources.
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The *relational* concept is connected with organizing information across multiple tables in the database.
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The *relationships* between tables in a database can be established (or even enforced) in different ways, through the use of keys and other constraints.
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In many small datasets we have only a few tables and we don't have to think about cross-references within datasets.
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The idea of *relational data* becomes more and more important as the amount and complexity of data grows. This provides the motivation for using relational databases: to organize data through related keys.
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## Databases
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### Why use relational databases

md5sum.txt

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"NEWS.md" "84aa522251c8b0043f12e83af45cc3d8" "site/built/NEWS.md" "2023-04-21"
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"config.yaml" "0928fbefeca4f51e54ccc3687a9565e9" "site/built/config.yaml" "2023-04-21"
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"index.md" "cfdee7444b27a96171c25e1d4915e1e9" "site/built/index.md" "2023-06-07"
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"episodes/00-sql-introduction.md" "702a6c1b841bc4729bb2d8e0b358532e" "site/built/00-sql-introduction.md" "2023-04-21"
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"episodes/00-sql-introduction.md" "854ebca592cc59c8d841d30d0fedc707" "site/built/00-sql-introduction.md" "2023-10-12"
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"episodes/01-sql-basic-queries.md" "31fc6d3e21d679cab6a002bffe7c182d" "site/built/01-sql-basic-queries.md" "2023-04-21"
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"episodes/02-sql-aggregation.md" "07784e3014a42660059c18e6ba71f26d" "site/built/02-sql-aggregation.md" "2023-04-21"
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"episodes/03-sql-joins.md" "4c87f9451d13eaa88c1b38fe29c7a7f3" "site/built/03-sql-joins.md" "2023-06-30"

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