sql函数返回标量值的例子

--创建数据表
6> CREATE TABLE Orders (
7>      OrderID int NOT NULL ,
8>      CustomerID nchar (5) NULL ,
9>      EmployeeID int NULL ,
10>     OrderDate datetime NULL ,
11>     requiredDate datetime NULL ,
12>     ShippedDate datetime NULL ,
13>     ShipVia int NULL ,
14>     Freight money NULL DEFAULT (0),
15>     ShipName nvarchar (40) NULL ,
16>     ShipAddress nvarchar (60) NULL ,
17>     ShipCity nvarchar (15) NULL ,
18>     ShipRegion nvarchar (15) NULL ,
19>     ShipPostalCode nvarchar (10) NULL ,
20>     ShipCountry nvarchar (15) NULL)
21> GO
1>
2>    CREATE FUNCTION DayOnly(@Date datetime)
3>    RETURNS varchar(12)
4>    AS
5>    BEGIN
6>       RETURN CONVERT(varchar(12), @Date, 101)
7>    END
8> GO
1>    SELECT *
2>    FROM Orders
3>    WHERE dbo.DayOnly(OrderDate) = dbo.DayOnly(GETDATE())
4> GO
OrderID     CustomerID EmployeeID  OrderDate               RequiredDate            ShippedDate             ShipVia     Freight               ShipName                                 ShipAddress
                                           ShipCity        ShipRegion      ShipPostalCode ShipCountry
----------- ---------- ----------- ----------------------- ----------------------- ----------------------- ----------- --------------------- ---------------------------------------- ------------------
------------------------------------------ --------------- --------------- -------------- ---------------

(0 rows affected)
1>
2> drop FUNCTION DayOnly;