How can I write this complex query SQL?

Question

If I know how to filter by all signs of the zodiac, then by the sign of the zodiac 'Capricorn' (from December 22 to January 20) I do not know how to select.

Here is the structure of the tables, do I need to select all users with the sign of the zodiac 'Capricorn'?

The structure of the tables can be changed (or even add new tables if required):

CREATE TABLE IF NOT EXISTS `horoscope` (
    `id` INT(11) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    `name` VARCHAR(255) NOT NULL UNIQUE,
    `date_start` VARCHAR(5),
    `date_end` VARCHAR(5)
);
CREATE INDEX `horoscope_idx_1` ON `horoscope`(`date_start`, `date_end`);

CREATE TABLE IF NOT EXISTS `user` (
    `id` INT(11) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    `name` VARCHAR(255) NOT NULL,
    `birthday` DATE NOT NULL
);

Insert test data

# Insert horoscope in table
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Aries', '03-21', '04-20');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Taurus', '04-21', '05-20');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Gemini', '05-22', '06-21');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Cancer', '06-22', '07-22');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Leo', '07-23', '08-23');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Virgin', '08-24', '09-22');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Libra', '08-23', '10-22');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Scorpio', '10-23', '11-21');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Sagittarius', '11-22', '12-21');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Capricorn', '12-22', '01-20');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Aquarius', '01-21', '02-19');
INSERT INTO `horoscope` (`name`, `date_start`, `date_end`) VALUES ('Pisces', '02-20', '03-20');

# Insert random user in table
DROP PROCEDURE IF EXISTS `add_user`;
CREATE PROCEDURE `add_user`(IN `count_user` INT)
    LANGUAGE SQL
    DETERMINISTIC
    SQL SECURITY DEFINER
    COMMENT 'A procedure for inserting random user'

BEGIN
    DECLARE i INT DEFAULT (
        SELECT `id`
        FROM `user`
        ORDER BY `id` DESC
        LIMIT 1
    );
    IF i IS NULL
        THEN SET i = 1;
    END IF;

    SET `count_user` = `count_user` + i;

    WHILE i <= `count_user` DO
        SET @`name` = CONCAT('user_', i);
        SET @`user_birth` = '1980-01-01' + INTERVAL (RAND() * 365 * 20) DAY;

        INSERT INTO `user` (`name`, `birthday`) VALUES (@`name`, @`user_birth`);

        SET i = i + 1;
    END WHILE;
END;
CALL `add_user`(1000);
DROP PROCEDURE IF EXISTS `add_user`;

Answer 1

I decided =)

SELECT *
FROM user as u
WHERE (
    DATE_FORMAT(u.birthday, '%m%d') >= (
        SELECT
            CONCAT(LEFT(`h`.`date_start`, 2), RIGHT(`h`.`date_start`, 2))
        FROM horoscope h
        WHERE h.name = 'Capricorn'
    ) AND DATE_FORMAT(u.birthday, '%m%d') <= 1231
) OR (
    DATE_FORMAT(u.birthday, '%m%d') >= 101 AND DATE_FORMAT(u.birthday, '%m%d') <= (
        SELECT
            CONCAT(LEFT(`h`.`date_end`, 2), RIGHT(`h`.`date_end`, 2))
        FROM horoscope h
        WHERE h.name = 'Capricorn'
    )
);

Answer 2

If the boundaries of each zodiac sign are fixed dates, then it would make sense to add birth-sign as an attribute to each user instead of filtering by dates each and every time you need that information.

However I would suggest the following if you do need to filter:

select *
from user u
inner join horoscope h
where (h.date_start > h.date_end 
       and u.birthday between str_to_date(concat(year(u.birthday)-1, h.date_start),'%Y%m-%d')
                          and str_to_date(concat(year(u.birthday), h.date_end),'%Y%m-%d')
   )
or (h.date_start < h.date_end 
    and u.birthday between str_to_date(concat(year(u.birthday), h.date_start),'%Y%m-%d')
                       and str_to_date(concat(year(u.birthday), h.date_end),'%Y%m-%d')
   )

Note however that the indexing of the 2 varchar(5) columns in horoscope probably isn't going to be helpful to your queries.

see: https://rextester.com/OAOTEH65480