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8 Commits

Author SHA1 Message Date
GuanM
8439ea1f37 数据的更改 2024-11-19 15:46:08 +08:00
GuanM
5ce0db0c27 基本SELECT查询 2024-11-19 15:44:09 +08:00
GuanM
155d5aa380 带限制条件的查询和表达式查询 2024-11-19 15:43:01 +08:00
GuanM
cbd24d1714 使用WHERE语句进行检索 2024-11-19 15:34:14 +08:00
GuanM
8bdb573a81 通配符_的使用 2024-11-19 15:29:55 +08:00
GuanM
81fed4392d 1. 通配符%的使用 2024-11-19 15:27:43 +08:00
GuanM
3fdd06a507 AVG() 函数的使用 2024-11-19 15:27:11 +08:00
GuanM
9ccd5e1a89 COUNT() 函数的使用 2024-11-19 15:25:25 +08:00
8 changed files with 155 additions and 0 deletions

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USE Mall
GO
SET NOCOUNT ON
------ return two columns that the price bigger than average price ------
-- ********** Begin ********** --
SELECT prod_name, prod_price
FROM Products
WHERE prod_price > (SELECT AVG(prod_price) FROM Products)
-- ********** End ********** --
GO

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USE Mall
GO
SET NOCOUNT ON
------ return the number of product which price bigger than 10 -----
-- ********** Begin ********** --
SELECT COUNT(*)
FROM Products
WHERE prod_price > 10
-- ********** End ********** --
GO

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USE Mall
Go
SET NOCOUNT ON
---------- retrieving with range ----------
-- ********** Begin ********** --
SELECT prod_name, prod_price
FROM Products
WHERE prod_price BETWEEN 3 AND 5;
-- ********** End ********** --
GO
---------- retrieving with nomatches ----------
-- ********** Begin ********** --
SELECT prod_name, prod_price
FROM Products
WHERE prod_name <> 'Lion toy';
-- ********** End ********** --
GO

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USE Mall
GO
SET NOCOUNT ON
---------- retrieving multiple column ----------
-- ********** Begin ********** --
SELECT prod_name, prod_price
FROM Products;
-- ********** End ********** --
GO
---------- retrieving all column ----------
-- ********** Begin ********** --
SELECT *
FROM Products;
-- ********** End ********** --
GO

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USE Mall
Go
SET NOCOUNT ON
---------- retrieving with limited ----------
-- ********** Begin ********** --
SELECT prod_name
FROM Products
WHERE prod_name LIKE '%toy%'
-- ********** End ********** --
GO
---------- retrieving with expression ----------
-- ********** Begin ********** --
SELECT prod_price, prod_price * 0.8 AS discount_price
FROM Products
WHERE prod_price > 3
-- ********** End ********** --
GO

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-- ********** create database ********** --
-- ********** Begin ********** --
create database Books
-- ********** End ********** --
go
use Books
go
-- ********** create table ********** --
-- ********** Begin ********** --
create table prices
(
ID int IDENTITY(1,1) not null,
Name varchar(20) not null,
price varchar(30) not null
)
-- ********** End ********** --
go
SET NOCOUNT ON
-- ********** insert ********** --
-- ********** Begin ********** --
insert into prices (Name, price) values ('Harry Potter', '$128')
insert into prices (Name, price) values ('Walden', '$5')
-- ********** End ********** --
go
SET NOCOUNT ON
-- ********** update ********** --
-- ********** Begin ********** --
update prices set price = '$6' where Name = 'Walden'
-- ********** End ********** --
go

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USE Mall
Go
SET NOCOUNT ON
---------- retrieving with wildcard % ----------
-- ********** Begin ********** --
SELECT prod_id, prod_name, prod_price
FROM Products
WHERE prod_name LIKE '%toy%'
-- ********** End ********** --
GO

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USE Mall
Go
SET NOCOUNT ON
---------- retrieving with wildcard _ ----------
-- ********** Begin ********** --
SELECT prod_id, prod_name, prod_price
FROM Products
WHERE prod_name LIKE '1_ inch%'
-- ********** End ********** --
GO