From ef9d8c30d68c6eb27f60d6e66bb16fa11829d805 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=90=B4=E6=AC=A3=E7=87=95?= <932306904@qq.com>
Date: Tue, 27 Sep 2022 23:21:22 +0800
Subject: [PATCH] =?UTF-8?q?31=E5=90=B4=E6=AC=A3=E7=87=95?=
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---
 .../\350\247\206\345\233\276.md"              | 85 +++++++++++++++++++
 .../2022.09.27\350\247\206\345\233\276.md"    | 62 ++++++++++++++
 2 files changed, 147 insertions(+)
 create mode 100644 "31\345\220\264\346\254\243\347\207\225/\344\275\234\344\270\232/\350\247\206\345\233\276.md"
 create mode 100644 "31\345\220\264\346\254\243\347\207\225/\347\254\224\350\256\260/2022.09.27\350\247\206\345\233\276.md"

diff --git "a/31\345\220\264\346\254\243\347\207\225/\344\275\234\344\270\232/\350\247\206\345\233\276.md" "b/31\345\220\264\346\254\243\347\207\225/\344\275\234\344\270\232/\350\247\206\345\233\276.md"
new file mode 100644
index 0000000..5758484
--- /dev/null
+++ "b/31\345\220\264\346\254\243\347\207\225/\344\275\234\344\270\232/\350\247\206\345\233\276.md"
@@ -0,0 +1,85 @@
+```
+use BankTest
+go
+
+--1）编写视图实现查询出所有银行卡账户信息，显示卡号，身份证，姓名，余额。
+create view v_account 
+as
+select CardNo,AccountCode,RealName,CardMoney from AccountInfo a
+join BankCard b on b.AccountId = a.AccountId
+go
+select * from v_account
+go
+
+
+--2）行转列常用做法: group by + sum(case when) /+count(case when)  数据分析+ over (paritition by, order by)
+--     提示：  pivot
+
+create database sec
+go
+use sec
+go
+create table secc
+(
+[year] int,
+[month] int,
+amount float
+)
+go
+insert into secc([year],[month],amount) values
+(1991,1,1.1),
+(1991,2,1.2),
+(1991,3,1.3),
+(1991,4,1.4),
+(1992,1,2.1),
+(1992,2,2.2),
+(1992,3,2.3),
+(1992,4,2.4)
+go
+select * from secc
+go
+
+------
+select * from secc
+pivot(
+MIN(amount) for [month] in ([1],[2],[3],[4])
+) as aa
+
+------
+select [year],
+MIN((case when [month] = 1 then amount else 404 end))m1,
+MIN((case when [month] = 2 then amount else 404 end))m2,
+MIN((case when [month] = 3 then amount else 404 end))m3,
+MIN((case when [month] = 4 then amount else 404 end))m4
+from secc
+group by [year]
+
+
+--列转行 union
+--drop table stu
+create table stu(
+name varchar(20),
+english int,
+maths int,
+music int
+)
+go
+
+insert into stu(name,english,maths,music) values
+('Jim',90,88,99)
+go
+
+-----
+select name,'english' [subject],90 score from stu
+union
+select name,'maths' [subject],88 score from stu
+union
+select name,'music' [subject],99 score from stu
+go
+
+-----
+select name,subject,score from stu
+unpivot(
+score for subject in(english,maths,music)
+)as 
+```
\ No newline at end of file
diff --git "a/31\345\220\264\346\254\243\347\207\225/\347\254\224\350\256\260/2022.09.27\350\247\206\345\233\276.md" "b/31\345\220\264\346\254\243\347\207\225/\347\254\224\350\256\260/2022.09.27\350\247\206\345\233\276.md"
new file mode 100644
index 0000000..fb1147f
--- /dev/null
+++ "b/31\345\220\264\346\254\243\347\207\225/\347\254\224\350\256\260/2022.09.27\350\247\206\345\233\276.md"
@@ -0,0 +1,62 @@
+2022.09.26视图(view)
+
+触发器，存储过程，proc
+
+为什么使用视图
+
+重用SQL语句 简化复杂的SQL操作 使用表的一部分而不是整个表 保护数据。可以授权用户访问表的特定部分的权限，而不是整个表的访问权限 更改数据格式和表示
+
+创建视图
+
+```
+create view 名字
+as +查询条件
+```
+
+利用视图简化复杂的联结
+
+```
+CREATE VIEW ProductCustomers AS
+SELECT cust_name,cust_contact,prod_id
+FROM customers,orders,orderItems
+WHERE customers.cust_id=orders.cust_id
+AND orderitems.order_num=orders.order_num;
+```
+
+用视图重新格式化检索出的数据
+
+```
+CREATE VendorLoactions AS
+SELECT RTRIM(vend_name)+'('+RTTIM(vend_country)+')' AS vend_title
+FROM Vendors;
+```
+
+用视图过滤不想要的数据
+
+```
+CREATE VIEW CustomersEMailList AS
+SELECT cust_id,cust_name,cust_email
+FROM customers
+WHERE Customers
+WHERE cust_email IS NOT NULL;
+```
+
+with check option
+
+涉及增删改查对视图的无法进行操作
+
+二级视图
+
+并集A,B表合并
+
+union 自动清除一个重复交集，共有的数据
+
+intersect
+
+差集
+
+except A-B=A表特有的数据
+
+列转行：union
+
+行转列：pivot
\ No newline at end of file
-- 
Gitee