try this:

DECLARE @A as TABLE(Eid VARCHAR(5),DocNo VARCHAR(5))

DECLARE @b-2 as TABLE(Cid VARCHAR(5),CDocNo VARCHAR(5))

DECLARE @C as TABLE(Did VARCHAR(5),EDocNo VARCHAR(5))

INSERT INTO @A

VALUES

('a','1'), ('a','2'),('a','4'), ('a','6'), ('c','3'), ('b','4'), ('e','5'),

('b','1'), ('b','3'), ('b','6')

INSERT INTO @b-2

VALUES

('a','1'), ('a','2'),...