SO-37949265

DECLARE @TableA TABLE (ID INT, Value VARCHAR(6));
    
INSERT  INTO @TableA
        (ID, Value)
VALUES  (1, 'Apple'),
        (2, 'Orange'),
        (3, 'Banana');


DECLARE @TableB TABLE (ID INT, Value VARCHAR(9));
    
INSERT  INTO @TableB
        (ID, Value)
VALUES  (6, 'Sorbet'),
        (7, 'Ice Cream');


DECLARE @TableC TABLE (A_ID INT, B_ID INT);
    
INSERT  INTO @TableC
        (A_ID, B_ID)
VALUES  (1, 7);

SELECT  A.ID AS A_ID,
        A.Value AS A_Value,
        CASE WHEN C.A_ID IS NOT NULL THEN 'Yes'
             ELSE 'No'
        END AS Mapped,
        B.ID AS B_ID,
        B.Value AS B_Value
FROM    @TableA A
LEFT JOIN @TableC C ON C.A_ID = A.ID
FULL OUTER JOIN @TableB B ON B.ID = C.B_ID;