----------------------------------------------------------基本--------------------------------------------------------------
1、SELECT（選取）
SELECT * FROM Persons WHERE firstname='Thomas' OR lastname='Carter'
2、INSERT（插入）
INSERT INTO Persons VALUES ('Gates', 'Bill', 'Xuanwumen 10', 'Beijing')
3、DELETE（刪除）
DELETE FROM Person WHERE LastName = 'Wilson'
4、UPDATE（修改）
UPDATE Person SET FirstName = 'Fred' WHERE LastName = 'Wilson'
----------------------------------------------------------高級--------------------------------------------------------------
1、TOP（返回記錄數目）
SELECT TOP 50 PERCENT * FROM Persons
2、LIKE（通配符）
SELECT * FROM Persons WHERE City NOT LIKE '%lon%'
3、AS（指定別名）
SELECT po.OrderID, p.LastName, p.FirstName FROM Persons AS p, Product_OrdersAS po
WHERE p.LastName='Adams' AND p.FirstName='John'
4、JOIN（連接，從兩個或更多的表中獲取結果）
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 Persons.LastName, Persons.FirstName, Orders.OrderNo FROM Persons RIGHT JOIN Orders ON Persons.Id_P=Orders.Id_P ORDER BY Persons.LastName
SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo FROM Persons FULL JOIN Orders ON Persons.Id_P=Orders.Id_P ORDER BY Persons.LastName
5、UNION（合併多個SELECT語句的結果）
SELECT E_Name FROM Employees_China UNION SELECT E_Name FROM Employees_USA
6、SELECT INTO（複製表）
SELECT *INTO Persons_backup FROM Persons
7、PRIMARY_KEY、FOREIGN_KEY（主鍵、外鍵）
CREATE TABLE Orders
(
O_Id int NOT NULL PRIMARY KEY,
OrderNo int NOT NULL,
Id_P int FOREIGN KEY REFERENCES Persons(Id_P)
)
8、CREATE（創建數據庫、表、索引）
CREATE DATABASE my_db
CREATE TABLE Persons(Id_P int,LastName varchar(255),FirstName varchar(255),Address varchar(255),City varchar(255))
CREATE INDEX PersonIndex ON Person (LastName)
9、DROP（刪除數據庫、表、索引）
DROP DATABASE m_db
DROP TABLE Persons
DROP INDEX PersonIndex ON Person
10、ALTER（添加、刪除、修改列）
ALTER TABLE Persons ADD Birthday date
ALTER TABLE Persons DROP Birthday date
ALTER TABLE Persons ALTER COLUMN Birthday year
11、ORDER BY（排序）
SELECT * FROM Persons ORDER BY FirstName DESC
----------------------------------------------------------函數--------------------------------------------------------------
1、AVG（均值）
SELECT Customer FROM Orders WHERE OrderPrice>(SELECT AVG(OrderPrice) FROM Orders)
2、MAX、MIN（最大、小值）
SELECT MAX(OrderPrice) AS LargestOrderPrice FROM Orders
3、FIRST、LAST（第一個、最後一個）
SELECT FIRST(OrderPrice) AS FirstOrderPrice FROM Orders
4、COUNT（行數）
SELECT COUNT(Customer) AS CustomerNilsen FROM OrdersWHERE Customer='Carter'
5、GROUP BY（根據一個或多個列對結果集進行分組）
SELECT Customer,OrderDate,SUM(OrderPrice) FROM Orders GROUP BY Customer,OrderDate
6、HAVING（條件選擇，因爲WHERE 關鍵字無法與合計函數一起使用）
SELECT Customer,SUM(OrderPrice) FROM Orders WHERE Customer='Bush' OR Customer='Adams'GROUP BY Customer HAVING SUM(OrderPrice)>1500
7、LACSE、UCASE（大小寫）
SELECT LCASE(LastName) as LastName,FirstName FROM Persons
8、LEN（文本段中值的長度）
SELECT LEN(City) as LengthOfCity FROM Persons
9、MID（從文本字段中提取子字符串）
SELECT MID(City,1,3) as SmallCity FROM Persons
10、ROUND（四捨五入）
SELECT ProductName, ROUND(UnitPrice,0) as UnitPrice FROM Products
11、NOW（當前時間）
SELECT ProductName, UnitPrice, Now() as PerDate FROM Products
SELECT ProductName, UnitPrice, FORMAT(Now(),'YYYY-MM-DD') as PerDateFROM Products