Home Database Mysql Tutorial SQL 必知必会笔记1了解SQL

SQL 必知必会笔记1了解SQL

Jun 07, 2016 pm 05:40 PM
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1.1 基本概念 数据库(DataBase) 保存有组织的数据库的容器(通常是一个文件或一组文件)。 表(Table) 某种特定数据类型的结构化清单。 模式(Schema) 关于数据库和表的布局及特性的信息。 列(Column) 表中的一个字段。所有表都是由一个或多个列组成的。 数据类

1.1 基本概念

数据库(DataBase)

保存有组织的数据库的容器(通常是一个文件或一组文件)。

表(Table)

某种特定数据类型的结构化清单。

模式(Schema)

关于数据库和表的布局及特性的信息。

列(Column)

表中的一个字段。所有表都是由一个或多个列组成的。

数据类型

所允许的数据库的类型。每个表都有相应的数据类型,它限制(或允许)该类中存储的数据。

行(Row)

表中的一个记录

主键

一列(或多列),其值能够唯一标准表中的每一行

满足以下条件的任何列都可以作为主键:

1.2 关于SQL

SQL 是一种专门用来与数据库沟通的语言。

SQL扩展

标准SQL由ANSI标准委员会管理,从而成为ANSI SQL。在ANSI SQL的基础上,所有主要的DBMS,美国空间,网站空间,香港服务器租用,在实现ANSI SQL的基础上都会有自己的扩展,例如:PL/SQL、Transact-SQL等。

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