问如果我要查询的行不存在，我可以返回NULL吗？

EN

DECLARE @MinDate DATE = '20110913',
        @MaxDate DATE = '20210913';

SELECT  TOP (DATEDIFF(DAY, @MinDate, @MaxDate) + 1)
        Date = DATEADD(DAY, ROW_NUMBER() OVER(ORDER BY a.object_id) - 1, 
@MinDate)
FROM    sys.all_objects a
        CROSS JOIN sys.all_objects b;

BEGIN TRANSACTION
BEGIN TRY

    CREATE TABLE #Users (
        Id INT NOT NULL IDENTITY(1,1) PRIMARY KEY, 
        [Name] NVARCHAR(50) NOT NULL
    )

    INSERT INTO #Users ([Name] )
    VALUES('Andrew'),
    ('Bob'), 
    ('Dave'), 
    ('Philip')

    SELECT * FROM #Users

    CREATE TABLE #Orders (
        Id INT NOT NULL IDENTITY(1,1) PRIMARY KEY, 
        UserId INT NOT NULL,
        Cost DECIMAL(18,2) NOT NULL,
        CONSTRAINT FK_Orders_Users FOREIGN KEY (UserId) REFERENCES #Users (Id) 
    )

    INSERT INTO #Orders (UserId, Cost) 
    VALUES(1, 2.99),
    (1, 5.99), 
    (4, 8.99)

    SELECT * FROM #Orders

    SELECT U.Id AS UserId, U.[Name], O.Id AS OrderId FROM #Users AS U
    LEFT JOIN #Orders AS O ON O.UserId = U.Id

    ROLLBACK TRANSACTION
END TRY
BEGIN CATCH
    PRINT 'Rolling back changes, there was an error!!' 
    ROLLBACK TRANSACTION
    DECLARE @Msg NVARCHAR(MAX)  
    SELECT @Msg=ERROR_MESSAGE() 
    RAISERROR('Error Occured: %s', 20, 101,@msg) WITH LOG
END CATCH