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关系代数和关系微积分的区别

关系代数和关系微积分的区别

关系代数关系微积分都是形式查询语言。

关系代数:
关系代数是一种过程语言。在关系代数中,顺序指定了必须执行的操作。在关系代数框架中创建来实现查询。关系代数中包含的基本运算是:

1. Select (σ)
2. Project (Π)
3. Union (U)
4. Set Difference (-)
5. Cartesian product (X)
6. Rename (ρ) 

关系演算:
关系微积分是正式的查询语言。它也被称为声明性语言。在关系演算中,没有指定必须执行运算的顺序。关系演算意味着我们必须获得什么结果。
关系微积分有两种变体:

  1. 元组关系演算 (TRC)
  2. 领域关系演算 (DRC)

关系微积分表示为:

{ t | P(t) }

Where,
t: the set of tuples
p: is the condition which is true for the given set of tuples.

关系代数和关系微积分的区别:

S.NO Relational Algebra Relational Calculus
1. It is a Procedural language. While Relational Calculus is Declarative language.
2. Relational Algebra means how to obtain the result. While Relational Calculus means what result we have to obtain.
3. In Relational Algebra, The order is specified in which the operations have to be performed. While in Relational Calculus, The order is not specified.
4. Relational Algebra is independent on domain. While Relation Calculus can be a domain dependent.
5. Relational Algebra is nearer to a programming language. While Relational Calculus is not nearer to programming language.

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