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---
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title: Databases [SQL]
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description:
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date: 2025-02-17T08:27:35+00:00
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draft: false
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tags:
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- programming
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A "table" written into a single file. The most common file type for this purpose is `CSV`.
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The `CSV` format reads each line as a row, and each comma-separated value as a column.
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The first row on a `CSV` file is used to describe the data in each column. If a `,` is present on the dataset, surround that entry with `"` to 'escape' it.
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These files can be read and written to using languages like [[c-language]] and [[python]].
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These files can be read and written to using languages like [c-language](../c-language.md) and [python](../python.md).
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## Relational Databases
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Instead of using a single table, a relational database can store data in multiple tables, and then define relationships between them.
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Each table must have one column with an unique key that identifies each row.
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![[image94.png]]
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### Relationships
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#### Many-to-many
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![[image95.png]]
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```SQL
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-- Select every person who starred in a show
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