SQL Server 2005新功能-TSQL
SQL Server 2005相對于SQL Server 2000改進很大,有些還是非常實用的。
舉幾個例子來簡單說明 這些例子我引用了Northwind庫。
1. TOP 表達式 SQL Server 2000的TOP是個固定值,是不是覺得不爽,現在改進了。
--前n名的訂單declare @n int; set @n = 10; select TOP(@n) * from Orders
2. 分頁 不知各位過去用SQL Server 2000是怎么分頁的,大多都用到了臨時表。SQL Server 2005一句話就支持分頁,性能據說也非常不錯。
--按Freight從小到大排序,求20到30行的結果; 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沒有異常,T-SQL必須逐行檢查錯誤代碼,對于習慣了try catch程序員,2005是不是更加親切:
SET XACT_ABORT ON; -- 打開 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. 通用表達式CTE 通過表達式可免除你過去創建臨時表的麻煩。www.mypchelp.cn
--例子:結合通用表達式進行分頁 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 特別,通過表達式還支持遞歸。
6. 直接發布Web Service 想要把store procedure變成Web Service就用這個吧,.NET, IIS都不需要,通過Windows 2003的HTTP Protocol Stack直接發布WebService,用這個功能需要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就發布好了,敲入http://localhost/sql/orders?wsdl得到wsdl
