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SQL学习(转载)

上一篇 / 下一篇  2014-08-18 13:25:12 / 个人分类:SQL学习

 第一范式:无重复的列
 第二范式:要求实体的属性完全依赖于主关键字,不能仅依赖于主关键字的一部分属性
 第三范式:要求一个数据库表中不含已在其他表中包含的非主关键字信息
 第四范式:禁止在主键和非主键之间存在独立的一对多关系

创建索引
create index sname_index
on employee(sname)

select * from employee
with (index(sname_index))


select sname from employee

select * from employee

select distinct sname from employee



SELECTDISTINCTCompany FROM Orders

SELECT * FROM PersonsWHERE City='Beijing'
SELECT * FROM Persons WHERE firstname='Thomas'ORlastname='Carter'
SELECT Company, OrderNumber FROM OrdersORDER BY Company, OrderNumber
INSERT INTO Persons VALUES ('Gates', 'Bill', 'Xuanwumen 10', 'Beijing')
UPDATE Person SET FirstName = 'Fred' WHERE LastName = 'Wilson'
DELETE FROM Person WHERE LastName = 'Wilson'
SELECTTOP 2* FROM Persons
SELECT * FROM Persons
WHERE City LIKE '%lon%'
SELECT * FROM Persons
WHERE FirstName LIKE '_eorge'
SELECT * FROM Persons
WHERE LastName IN ('Adams','Carter')
SELECT * FROM Persons
WHERE LastName
BETWEEN'Adams'AND'Carter'
SELECT po.OrderID, p.LastName, p.FirstName
FROM PersonsAS p, Product_OrdersAS po
WHERE p.LastName='Adams' AND p.FirstName='John'
SELECT Product_Orders.OrderID, Persons.LastName, Persons.FirstName
FROM Persons, Product_Orders
WHERE Persons.LastName='Adams' AND Persons.FirstName='John'
SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo
FROM Persons, Orders
WHERE Persons.Id_P = Orders.Id_P
SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo
FROM Persons
INNER JOIN Orders
ON Persons.Id_P=Orders.Id_P
ORDER BY Persons.LastName
SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo
FROM Persons
LEFT JOIN Orders
ON Persons.Id_P=Orders.Id_P
ORDER BY Persons.LastName
SELECT E_Name FROM Employees_China
UNION
SELECT E_Name FROM Employees_USA
SELECT INTO语句从一个表中选取数据,然后把数据插入另一个表中
SELECTLastName,FirstName
INTOPersons_backup
FROM Persons
CREATE DATABASE database_name
CREATE TABLE Persons
(
Id_P int,
LastName varchar(255),
FirstName varchar(255),
Address varchar(255),
City varchar(255)
)
CREATE INDEX PersonIndex
ON Person (LastName)
SELECT Customer,SUM(OrderPrice) FROM Orders
GROUP BY Customer
SELECT Customer,SUM(OrderPrice) FROM Orders
GROUP BY Customer
HAVING SUM(OrderPrice)<2000
SELECT Customer FROM Orders
WHERE OrderPrice>(SELECT AVG(OrderPrice) FROM Orders)


 


 


 




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wchair

wchair

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