| 1 | Now What?! World Tour | 1 | 2013-01-21 | 2013-01-26
| 2 | Dummy  | 1 | 2013-03-01 | 2013-03-04

SELECT
  t.id, t.title, t.group_id, d.begin_date, d.end_date
FROM
  tours t
INNER JOIN
  ( SELECT MIN(date) AS begin_date,
           MAX(date) AS end_date,
           tour_id
     FROM concerts
  ) d
ON t.id = d.tour_id
WHERE t.group_id = 1;

| 1 | Now What?! World Tour | 1 | 2013-01-21 | 2013-01-26

CREATE TABLE groups (
  id 	INT PRIMARY KEY NOT NULL,
  title CHAR(50) NOT NULL
);

INSERT INTO groups VALUES ( 1, "Deep Purple");
INSERT INTO groups VALUES ( 2, "Dummy");

CREATE TABLE tours (
  id 		INT PRIMARY KEY NOT NULL,
  title 	CHAR(50) NOT NULL,
  group_id	INT NOT NULL
);

INSERT INTO tours VALUES ( 1, "Now What?! World Tour", 1);
INSERT INTO tours VALUES ( 2, "Dummy", 1);

CREATE TABLE concerts (
  id 		INT PRIMARY KEY NOT NULL,
  country	CHAR(50),
  city		CHAR(50),
  date		DATETIME NOT NULL,
  tour_id	INT NOT NULL
);

INSERT INTO concerts VALUES ( 1, 'ОАЭ', 'Дубай', '2013-01-21', 1);
INSERT INTO concerts VALUES ( 2, 'Новая Зеландия', 'Окленд', '2013-01-24', 1);
INSERT INTO concerts VALUES ( 3, 'Австралия', 'Брисбен', '2013-01-26', 1);
INSERT INTO concerts VALUES ( 4, 'Австралия', 'Мельбурн', '2013-03-01', 2);
INSERT INTO concerts VALUES ( 5, 'Австралия', 'Сидней', '2013-03-02', 2);
INSERT INTO concerts VALUES ( 6, 'Австралия', 'Аделаида', '2013-03-04', 2);