sql最简单的查询语句

-- 2 **************************************************** -- 最简单的查询语句

-- 2.1 --------------------------------------------------

-- 使用 select 语句查询表中的数据

-- select * from table_name

use pubs

-- 切换当前数据库 select * from authors

-- 2.2 --------------------------------------------------

-- 使用完全限定名称

-- select * from [server_name].[database_name].[owner].[object]

select * from northwind.dbo.employees

select * from northwind..orders

-- 2.3 --------------------------------------------------

-- 查询数据表中指定的列 -- select column_1,column_2 from table_name

select * from authors select au_id,au_lname,au_fname,city from authors

-- 2.4 --------------------------------------------------

-- 使用 where 字句筛选指定的行

-- select * from table_name where <search_condition>

select * from jobs

select * from jobs where job_id=7

select * from authors

select * from authors where au_lname = 'white'

-- 2.5 --------------------------------------------------

-- where 字句中的搜索条件

-- 比较操作符    =, <, >, <=, >=, <>

-- 字符串比较符  like, not like

-- 逻辑操作符    and, or, not

-- 值的域        between, not between

-- 值的列表      in, not in

-- 未知的值      is null, is not null

select * from jobs where job_id >=10

select * from jobs where job_desc like '%manager%'

select * from jobs where job_id >=10 and job_desc like '%manager%'

select * from jobs where min_lvl between 100 and 150

select * from jobs where job_id in (1,3,5,7,11,13)

select * from discounts where stor_id is null

-- 2.6 --------------------------------------------------

-- 使用 like

-- %   代表 0 个或多个字符串

-- _   代表任何单个的字符

-- []  代表指定区域内的任何单个字符

-- [^] 代表不在指定区域内的任何单个字符

select * from authors where au_lname like 'g%'

select * from authors where address like '%av.%'

select * from authors where au_fname like 'a__'

select * from authors where au_fname like '[as]%'

select * from authors where au_lname like 's[^m]%'

-- 2.7 --------------------------------------------------

-- 格式化结果集

-- order by  排序结果集

-- distinct  消除重复的行

-- as        改变字段的名字

select * from employee order by fname

select * from employee order by hire_date desc

select distinct type from titles

select au_id,au_lname as [last name],au_fname as [first name] from authors