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, , Transact-SQL, .
MS SQL Server 3 :
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CREATE FUNCTION function_name
(
[ { @parameter_name [ AS ] parameter_data_type
[ = default ] }
[,...n ]
]
)
RETURNS return_data_type
[ WITH [ ENCRYPTION ] [ SCHEMABINDING ] [ EXECUTE AS Clause ]]
[ AS ]
BEGIN
function_body
RETURN scalar_expression
END
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:
. ProductCategoryID .
CREATE FUNCTION getMaxPrice (@ProductCategoryID int)
RETURNS int
AS
BEGIN
DECLARE @ret int;
SELECT @ret = MAX(Price)
FROM Product
WHERE ProductCategoryID = @ProductCategoryID
IF (@ret IS NULL)
SET @ret = 0;
RETURN @ret;
END;
--
SELECT ProductCategoryName, getMaxPrice (ProductCategoryID) AS MaxPrice
FROM ProductCategory
WHERE ProductCategoryID = 1;
