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What is an SQL relation?

PostgreSQL 作者:husthxd 时间:2019-09-12 16:04:43 0 删除 编辑

In SQL, a relation is a bag of objects that all share the same characteristics: a list of attributes with a known given data type.
We name those objects tuples in SQL. An object with three attributes can be named a triple, an object with four attributes a quadruple, with six attributes a sextuple, etc. The generic that applies to any number of attributes is built on the same mechanism. Let’s say that we have the unknown number t of attributes. Then we’ll name the object a T-UPLE, or a tuple.

What is an SQL relation?

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