Datos de prueba para UNION y UNION ALL en SELECT

CREATE TABLE A
  (
    numero numeric NOT NULL,
    texto char(40) NOT NULL,
    fecha datetime
            PRIMARY KEY (numero)    
  );

CREATE TABLE B
  (
    numero numeric NOT NULL,
    texto char(40) NOT NULL,
    fecha datetime
            PRIMARY KEY (numero)    
  );

  CREATE TABLE C
  (
    numero numeric NOT NULL,
    texto char(40) NOT NULL,
    fecha datetime
            PRIMARY KEY (numero)    
  );


INSERT INTO A VALUES ('1','UNO'   ,'2018-01-01 00:00:00.000');
INSERT INTO A VALUES ('2','DOS'   ,'2018-02-01 00:00:00.000');
INSERT INTO A VALUES ('3','TRES'  ,'2018-03-01 00:00:00.000');
INSERT INTO A VALUES ('4','CUATRO','2018-04-01 00:00:00.000');
INSERT INTO A VALUES ('5','CINCO' ,'2018-05-01 00:00:00.000');
INSERT INTO A VALUES ('6','SEIS'  ,'2018-06-01 00:00:00.000');

INSERT INTO B VALUES ('1','UNO'  ,'2018-01-01 00:00:00.000');
INSERT INTO B VALUES ('2','DOS'  ,'2018-02-02 00:00:00.000');
INSERT INTO B VALUES ('3','III'  ,'2018-03-03 00:00:00.000');
INSERT INTO B VALUES ('44','XLIV','2018-04-04 00:00:00.000');
INSERT INTO B VALUES ('54','LIV' ,'2018-05-05 00:00:00.000');
INSERT INTO B VALUES ('64','LXIV','2018-06-06 00:00:00.000');

INSERT INTO C VALUES ('11','11'  ,'2018-01-11 00:00:00.000');
INSERT INTO C VALUES ('21','21'  ,'2018-02-21 00:00:00.000');
INSERT INTO C VALUES ('31','31'  ,'2018-03-31 00:00:00.000');
INSERT INTO C VALUES ('44','XLIV','2018-04-04 00:00:00.000');
INSERT INTO C VALUES ('54','LIV' ,'2018-05-05 00:00:00.000');
INSERT INTO C VALUES ('64','LXIV','2018-06-06 00:00:00.000');