CREATE TABLE Table_1 (
    Id INTEGER PRIMARY KEY  AUTOINCREMENT  NOT NULL ,
    EmailId VARCHAR
)

INSERT INTO Table_1 VALUES (1,'raj@gmail.com');
INSERT INTO Table_1 VALUES (3,'test@gmail.com');
INSERT INTO Table_1 VALUES (4,'false5@gmail.com');
INSERT INTO Table_1 VALUES (7,'false55@gmail.com');
INSERT INTO Table_1 VALUES (8,'falsefalse@gmail.com');
INSERT INTO Table_1 VALUES (9,'true1@gmail.com');
INSERT INTO Table_1 VALUES (11,'true2@gmail.com');
INSERT INTO Table_1 VALUES (12,'falsefalsefalse@gmail.com');
INSERT INTO Table_1 VALUES (13,'ravi@gmail.com');
INSERT INTO Table_1 VALUES (14,'rak@gmail.com');
INSERT INTO Table_1 VALUES (15,'false@gmail.com');
INSERT INTO Table_1 VALUES (16,'false66@gmail.com');


CREATE TABLE Table_2 (
    Id INTEGER PRIMARY KEY  AUTOINCREMENT  NOT NULL ,
    EmailId VARCHAR
)

INSERT INTO Table_2 VALUES (1,'raj@gmail.com');
INSERT INTO Table_2 VALUES (3,'test@gmail.com');
INSERT INTO Table_2 VALUES (4,'false98@gmail.com');
INSERT INTO Table_2 VALUES (7,'abc@gmail.com');
INSERT INTO Table_2 VALUES (8,'ta@gmail.com');
INSERT INTO Table_2 VALUES (9,'false1@gmail.com');
INSERT INTO Table_2 VALUES (11,'false2@gmail.com');
INSERT INTO Table_2 VALUES (12,'false@gmail.com');
INSERT INTO Table_2 VALUES (13,NULL);
INSERT INTO Table_2 VALUES (14,NULL);
INSERT INTO Table_2 VALUES (15,'false@gmail.com');
INSERT INTO Table_2 VALUES (16,'false66@gmail.com');

UPDATE Newcontacts n
  JOIN DummyContacts d  ON (n.Id=d.Id)
SET n.EmailId=d.EmailId
WHERE n.EmailId<>d.EmailId
  OR d.EmailId IS NOT NULL

UPDATE Table_1
SET EmailId = (SELECT d.EmailId
                 FROM Table_2 d
                 WHERE Table_1.Id = d.Id
                 )
WHERE EXISTS (SELECT d.EmailId
                 FROM Table_2 d
                 WHERE Table_1.Id = d.Id
                   AND Table_1.EmailId <> d.EmailId
                   AND d.EmailId IS NOT NULL
                 );