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前言

关系数据库 mysql sqlserver orcel

SQL语句基本构成

SELECT *
FROM customers
-- WHERE  customer_id = 1 //-- 注释符号
ORDER BY first_name

SELECT子句

SELECT
first_name, 
last_name, 
points , 
(points+10) *100  AS 'discount_factor' //对某一列进行计算, 或者处理 AS 添加描述
FROM customers

SELECT DISTINCT state //DISTINCT 去重复 distinct
FROM customers

exercise

SELETCT *
FROM products

SELECT 
name,
FROM products

SELECT DISTINCT price
FROM products

SELECT  price *1.1 AS new price
FROM produts

WHERE 子句

SELECT * 
FROM  customers
WHERE points>30  // > >=  < <=  =  <>

SELECT *
FROME customers
WHERE birth_date >'1991-09-08' //'1991-12-31' 是标准时间格式

exercise

SELECT * 
FROM orders
WHERE ORDER_DATE>='1991-08-08'

AND OR NOT 运算符

SELECT *
FROM customers
WHERE birth_date> '1991-09-08' OR 
(points>1000 AND state= 'va') // and 有更高的优先级

SELECT *  // not 使用方式
FROM customers
WHERE NOT(birth_date>'1991-09-08' or points<1000)

//NOT(birth_date>'1991-09-08' or points<1000) 等效于
birth_date<='1991-09-08' and points >=1000)

exercise

SELECT *
FROM order_items
WHERE order_id = 6 AND unit_price *quantiy > 30

IN 运算符号

SELECT * 
FROM customers
WHERE state in ('VA','GA','FL')  // 等效 state = 'va' or state = 'ga' or state = 'fl'

exercise

SELECT *
FROM products
WHERE quantity in (49,38,72)

BETWEEN 运算符号

SELECT *
FROM customers
where points BETWEEN 1000 AND 3000  // 1000-3000

exercise

SELECT *
FROM customers
WHERE birth_date BETWEEN ''1990-01-01" AND "2000-01-01"

LIKE 子句

SELECT *
FROM customers
 WHERE last_name LIKE 'B%' // ''%B% 任意位置, %b结尾是b , _y 不在乎低位是什么第二位是y "_" 代表一个占位符号, b___y 开头是b结尾是y,中间三个占位

-- % any number of characters
-- _ single character

exercise

SELECT * 
FROM customers
WHERE address LIKE '%TRAIL%' OR address LIKE '%AVENUE%'  AND
phone_num LIKE '%9' // 取反 NOT LIKE

REGEXP 运算符
regular expression

SELECT *
FROM customers
WHERE last_name REGXP  'field'  // ^ $

'field | mac' 或者 or
'^field' 需要field 开头
'field$'  需要field 结尾
'[gim]e' e前面有 g , I , m
'e[fmq]' e后面有 f, m, q
'[a-h]e'
-- ^ beginning
-- $ end
-- | logic or
-- [abcd]
-- [a-f]

exercise

SELECT *
FROM customers
WHERE first_name REGXP 'ELKA|AMBUR'


SELECT *
FROM customers
WHERE last_name REGXP 'ey$|on$'  //'' ey on结尾

SELECT *
FROM customers
WHERE last_name REGXP '^my|se'  //'' ey on结尾

SELECT *
FROM customers
WHERE last_name REGXP 'b[ru]'  //'' ey on结尾

IS NULL 运算符号

SELECT *
FROM customers
WHERE phone IS NULL

exercise

SELECT *
FROM orders
WHERE ship_id IS NULL

ORDER BY 子句

SELECT *
FROM customers
ORDER BY fist_name desc , last_name aesc //desc 倒序 aesc 正序

exercise

SELECT * , quantity *unit_price AS total_price
FROM order_items
WHERE order_id = 2
ORDER BY totle_price DESC

LIMIT 子句

SELECT *
FROM customers
LIMIT 300  //sqlserver 使用 TOP 关键字

SELECT *
FROM customers
LIMIT 6,3 // skip 6 take 3

  • 按 Win + R 组合键，可以快速打开运行；
  • 打开的运行窗口中，输入： regedit 命令，确定或回车，可以快速打开注册表编辑器；

  • 注册表编辑器窗口中，依次展开到以下位置：

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\Profiles

  • 继续往下，展开Profiles 后， 你可以看见一个或多个子项，其中每一项就代表一个网络。 选中需要修改的子项后，在右侧会出现一系列注册表键值，其中 ProfileName 就是网络名称，双击打开并输入你想修改的名字，点击确定即可；

###使用powershell 依次执行以下命令，如果提示激活不成功，请尝试替换激活服务器kms.loli.best

slmgr /ipk W269N-WFGWX-YVC9B-4J6C9-T83GX 

slmgr /skms kms.loli.best

slmgr /ato
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