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