标签:style blog color io os ar for 数据 div
表类型简化了表变量的定义。通过创建表类型,可以把表的定义保存到数据库中,以后在定义表变量,存储过程和用户定义函数的输入参数时,就可以将表类型作为表的定义而重用。
下面的示例演示了如何通过表类型来简化表变量的定义,并且如何重用它。
USE TSQLFundamentals2008; GO IF TYPE_ID(‘dbo.OrderTotalsByYear‘) IS NOT NULL DROP TYPE dbo.OrderTotalsByYear; GO -- 创建表类型 CREATE TYPE dbo.OrderTotalsByYear AS TABLE ( orderyear INT NOT NULL PRIMARY KEY, qty INT NOT NULL ); -- 通过表类型创建表变量,并且填充数据 DECLARE @MyOrderTotalsByYear AS dbo.OrderTotalsByYear; INSERT INTO @MyOrderTotalsByYear( orderyear,qty ) SELECT YEAR(orders.orderdate)AS orderdate,SUM(orderdetails.qty) AS qty FROM Sales.Orders AS orders LEFT JOIN Sales.OrderDetails AS orderdetails ON orders.orderid = orderdetails.orderid GROUP BY YEAR(orders.orderdate); SELECT * FROM @MyOrderTotalsByYear;
查询结果:
标签:style blog color io os ar for 数据 div
原文地址:http://www.cnblogs.com/mcgrady/p/3981868.html