电脑技术学习

SQL Server 2005新功能-TSQL

dn001

SQL Server 2005相对于SQL Server 2000改进很大,有些还是非常实用的。

举几个例子来简单说明 这些例子我引用了Northwind库。

1. TOP 表达式
SQL Server 2000的TOP是个固定值,是不是觉得不爽,现在改进了。

--前n名的订单
declare @n int;
set @n = 10;
select TOP(@n) * from Orders

2. 分页
不知各位过去用SQL Server 2000是怎么分页的,大多都用到了临时表。SQL Server 2005一句话就支持分页,性能据说也非常不错。


--按Freight从小到大排序,求20到30行的结果;
select * from(;
select OrderId, Freight, ROW_NUMBER() OVER(order by Freight) as row from Orders;
) a;
where row between 20 and 30

3. 排名


select * from(;
select OrderId, Freight, RANK() OVER(order by Freight) as rank from Orders;
) a;
where rank between 20 and 30

4. try ... catch
SQL Server 2000没有异常,T-SQL必须逐行检查错误代码,对于习惯了try catch程序员,2005是不是更加亲切:


SET XACT_ABORT ON; -- 打开 try功能;
BEGIN TRY;
begin tran;
insert into Orders(CustomerId) values(-1);
commit tran;
print 'commited';
END TRY;
BEGIN CATCH;
rollback;;
print 'rolled back';
END CATCH

5. 通用表达式CTE
通过表达式可免除你过去创建临时表的麻烦。
www.mypchelp.cn


--例子:结合通用表达式进行分页
WITH OrderFreight AS(;
select OrderId, Freight, ROW_NUMBER() OVER(order by Freight) as row from Orders;
);
select OrderId, Freight from OrderFreight where row between 10 and 20
特别,通过表达式还支持递归。


6. 直接发布Web Service
想要把store procedure变成Web Service就用这个吧,.NET, IIS都不需要,通过Windows 2003的HTTP Protocol Stack直接发布WebService,用这个功能需要Windows 2003 sp1

--DataSet CustOrdersOrders(string customerID);
CREATE ENDPOINT Orders_Endpoint;
state=started;
as http(;
path='/sql/orders',;
AUTHENTICATION=(INTEGRATED),;
ports=(clear);
);
for soap(;
WebMethod 'CustOrdersOrders'(;
name='Northwind.dbo.CustOrdersOrders';
),;

wsdl=default,;
database='Northwind',;
namespace='http://mysite.org/';
)
Web Service就发布好了,敲入http://localhost/sql/orders?wsdl得到wsdl