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diff --git a/programming/about_relational_databases.md b/programming/about_relational_databases.md deleted file mode 100644 index 464de330..00000000 --- a/programming/about_relational_databases.md +++ /dev/null @@ -1,30 +0,0 @@ -# About relational databases - -## What is a relation? - -A common misconception is that the "relations" in a relational database are about relations between database tables. - -Actually, the relations in a relational database are the tables. - -A relation "relates" a set of values with another set of values. - -For example, a relation can relate the name of a person with their birth date and birth place. -For example: - -``` -(person name) => (birth date, birth place) -(Alice) => (1979-12-03, Barcelona) -(Bob) => (1995-03-04, Paris) -... -``` - -Many computer languages have similar concepts: - -* [Python mapping types such as `dict`](https://docs.python.org/3/library/stdtypes.html#mapping-types-dict) -* C++ `std::map` -* Java `java.util.Map` -* [C# `System.Collections.Generic.Dictionary`](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2?view=net-9.0) -* [Javascript `Object`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) -* [PHP arrays](https://www.php.net/manual/en/language.types.array.php) - -Relations are a natural concept, so although non-relational data systems exist, most data can be stored as relations. |