-- create a table to run the function against
CREATE TABLE test2 (id INT, col1 CHAR(1))

GO

-- create the TVF
CREATE FUNCTION test (@id INT)
RETURNS @table TABLE (id INT, col1 CHAR(1))
AS BEGIN

    INSERT INTO
        @table
        SELECT
            *
        FROM
            test2 AS T
        WHERE
            id = @id ;

    RETURN 
   END

GO

-- table variable for outer/left input
DECLARE @test1 TABLE (id INT, col1 CHAR(1))

-- insert test data
INSERT INTO
    @test1 (id, col1)
    SELECT TOP 10
        ROW_NUMBER() OVER (ORDER BY OBJECT_ID),
        CHAR(ROW_NUMBER() OVER (ORDER BY OBJECT_ID) + 60)
    FROM
        sys.all_columns AS AC 
    
INSERT INTO
    test2 (id, col1)
    SELECT TOP 10
        ROW_NUMBER() OVER (ORDER BY OBJECT_ID),
        CHAR(ROW_NUMBER() OVER (ORDER BY OBJECT_ID) + 60)
    FROM
        sys.all_columns AS AC 
    
-- cross join Cartesian product    
SELECT
    *
FROM
    @test1 CROSS JOIN
    test2
 
-- outer apply on a derived table   
SELECT
    *
FROM
    @test1 AS one CROSS APPLY
    (
     SELECT
        *
     FROM
        test2 AS two
     WHERE
        one.id = two.id
    ) AS test2 
    
-- outer apply TVF
SELECT
    *
FROM
    @test1 AS one CROSS APPLY
    dbo.test(one.id) ;
 
DROP TABLE test2 ;
 GO
DROP FUNCTION dbo.test ;