Lecture 3 SQL语言part1

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表定义、基本SQL查询

主要内容：

SQL(Structured Query Language) 是关系数据库标准语言,包括数据定义、数据操纵、数据控制一体化管理功能。SQL是一种陈述式的语言。讲授SQL的表定义，包括：SQL基本数据类型、primary key、foreign key和check定义，以及SQL DML语句的基本用法，包括select、from、where、group by、having各子句。

作业3：书后习题 3.8、3.9

关系代数只是用来描述，实际还是用sql写

• Lecture 3 SQL语言part1
  • 历史
  • 数据类型
  • Table Construct
  • *SQL and Relational Algebra
  • Basic Query Structure
    • The select Clause
    • The where Clause
      • Where Clause Predicates
    • The from Clause
    • Joins
    • Natural Joins
    • The Rename Operation
    • String Operations
    • Ordering the Display of Tuples
    • The limit Clause
    • Duplicates
  • Set Operations
  • Null Values
  • Aggregate Functions
    • Aggregate Functions – Group By
    • Aggregate Functions – Having Clause
    • Null Values and Aggregates
    • Arithmetric expression with Aggregate functions
  • Nested Subqueries
    • Set Membership
    • Set Comparison
    • Definition of Some Clause
    • Definition of all Clause
    • Scalar Subquery
    • Test for Empty Relations
    • Correlation Variables
    • Not Exists
    • Test for Absence of Duplicate Tuples
    • *Subqueries in the From Clause
    • *With Clause
    • *Complex Queries using With Clause

历史

sql标准非强制，主要是指导

书上的例子语法不一定正确（方言）

数据类型

Table Construct

reference 表示被引用时执行

cascade （一个过程中前一个引发后一个的）连续阶段

属于动作，类似递归这类的描述

还有三种动作（红色字体）

重新听一下考试考过的地方

*SQL and Relational Algebra

Basic Query Structure

The select Clause

The where Clause

Where Clause Predicates

The from Clause

Joins

Natural Joins

The Rename Operation

String Operations

Ordering the Display of Tuples

The limit Clause

Duplicates

Set Operations

Null Values

Aggregate Functions

Aggregate Functions – Group By

Aggregate Functions – Having Clause

上面这个例子包含了sql六大基本语句

这一部分都没听

Null Values and Aggregates

Arithmetric expression with Aggregate functions

Nested Subqueries

Set Membership

Set Comparison

Definition of Some Clause

Definition of all Clause

Scalar Subquery

Test for Empty Relations

Correlation Variables

Not Exists

Test for Absence of Duplicate Tuples

*Subqueries in the From Clause

*With Clause

*Complex Queries using With Clause