如果SQL Server CASE值为NULL，则不返回任何内容(To not return anything if SQL Server CASE value is NULL)

 我有一个函数根据某些条件返回一列中的多行数据。 
 
ALTER FUNCTION [dbo].[GetFavoriteFruits]
(   
    @FruitId uniqueidentifier
)
RETURNS TABLE 
AS
RETURN 
(
    Select Name FROM Fruits WHERE FruitID = @FruitId
    UNION ALL
    Select Name FROM Vegetables WHERE VegetableID = @FruitId
    UNION ALL
    Select
    CASE
    WHEN EXISTS(Select Name FROM Fruits WHERE FruitID = @FruitId) THEN 'Fruit Exists'
    END
    UNION ALL
    Select
    CASE
    WHEN EXISTS(Select Name FROM Vegetables WHERE VegetableID = @FruitId) THEN 'Vegetable Exists'
    END
    UNION ALL
    Select
    CASE
    WHEN EXISTS(Select Name FROM Fruits WHERE FruitID = @FruitId) OR EXISTS(Select Name FROM Vegetables WHERE VegetableID = @FruitId) THEN 'Either Fruit or Vegetable exists'
    END
)
 
 当桌子上有水果和蔬菜的价值时，每件事情都很好。 但是，如果前两种情况的值不存在，则返回的输出（来自最后3个查询）是 
 
NULL
NULL
NULL
 
 有没有一种方法可以避免这些NULL，并返回类似于前两个查询的任何内容。 

I have a function which returns multiple rows of data with one column based on certain conditions.
 
ALTER FUNCTION [dbo].[GetFavoriteFruits]
(   
    @FruitId uniqueidentifier
)
RETURNS TABLE 
AS
RETURN 
(
    Select Name FROM Fruits WHERE FruitID = @FruitId
    UNION ALL
    Select Name FROM Vegetables WHERE VegetableID = @FruitId
    UNION ALL
    Select
    CASE
    WHEN EXISTS(Select Name FROM Fruits WHERE FruitID = @FruitId) THEN 'Fruit Exists'
    END
    UNION ALL
    Select
    CASE
    WHEN EXISTS(Select Name FROM Vegetables WHERE VegetableID = @FruitId) THEN 'Vegetable Exists'
    END
    UNION ALL
    Select
    CASE
    WHEN EXISTS(Select Name FROM Fruits WHERE FruitID = @FruitId) OR EXISTS(Select Name FROM Vegetables WHERE VegetableID = @FruitId) THEN 'Either Fruit or Vegetable exists'
    END
)
 
When there are values for Fruits and Vegetables in the table, every thing is fine. But if the value for first two cases are not present then the output returned(from last 3 queries) is 
 
NULL
NULL
NULL
 
Is there a way I can avoid those NULL and return nothing similar to the first two queries.

原文：https://stackoverflow.com/questions/49058740