SQL（一）

public class SQL {

/**
* 1.distinct
* 去除重复
*/
String distinct = "select distinct Company from Orders";

/**
* 2.where
* SELECT 列名称 FROM 表名称 WHERE 列 运算符 值
* 操作符：=、 >、 <、 >=、 <=、 BETWEEN、 LIKE
*/
String where = "SELECT * FROM Persons WHERE City='Beijing'";

/**
* 3.AND & OR
*/
String and = "SELECT * FROM Persons WHERE FirstName='Thomas' AND LastName='Carter'";
String or = "SELECT * FROM Persons WHERE firstname='Thomas' OR lastname='Carter'";

/**
* 4.order by
* 根据指定的列对结果集进行排序
* 如果希望按照降序对记录进行排序，可以使用 DESC 关键字
*/
String orderBy1 = "SELECT Company, OrderNumber FROM Orders ORDER BY Company";
String orderBy2 = "SELECT Company, OrderNumber FROM Orders ORDER BY Company, OrderNumber";
String orderBy3 = "SELECT Company, OrderNumber FROM Orders ORDER BY Company DESC";
String orderBy4 = "SELECT Company, OrderNumber FROM Orders ORDER BY Company DESC, OrderNumber ASC";

/**
* 5.insert
* INSERT INTO 表名称 VALUES (值1, 值2,....)
* INSERT INTO table_name (列1, 列2,...) VALUES (值1, 值2,....)
*/
String insert1 = "INSERT INTO Persons VALUES ('Gates', 'Bill', 'Xuanwumen 10', 'Beijing')";
String insert2 = "INSERT INTO Persons (LastName, Address) VALUES ('Wilson', 'Champs-Elysees')";

/**
* 6.update
* UPDATE 表名称 SET 列名称 = 新值 WHERE 列名称 = 某值
*/
String update1 = "UPDATE Person SET FirstName = 'Fred' WHERE LastName = 'Wilson' ";
String update2 = "UPDATE Person SET Address = 'Zhongshan 23', City = 'Nanjing' WHERE LastName = 'Wilson";

/**
* 7.delete
* DELETE FROM 表名称 WHERE 列名称 = 值
*/
String delete1 = "DELETE FROM Person WHERE LastName = 'Wilson' ";
String delete2 = "DELETE * FROM table_name";

/**
* 8.like操作符
*/
String like = "SELECT * FROM Persons WHERE City LIKE '%N%'";

/**
* 9.in操作符
*/
String in = "SELECT * FROM Persons WHERE LastName IN ('Adams','Carter')";

/**
* 10.join操作符（inner join, left join, right join）
* 有时为了得到完整的结果，我们需要从两个或更多的表中获取结果。我们就需要执行 join。
*/
String not_join 	= "SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo"
+ "FROM Persons, Orders"
+ "WHERE Persons.Id_P = Orders.Id_P ";

String inner_join	= "SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo"
+ "FROM Persons INNER JOIN Orders ON Persons.Id_P = Orders.Id_P";

String left_join 	= "SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo"
+"FROM Persons LEFT JOIN Orders ON Persons.Id_P=Orders.Id_P";

String right_join 	= "SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo"
+"FROM Persons RIGHT JOIN Orders ON Persons.Id_P=Orders.Id_P";

}