CREATE TABLE rabotniki
(man_id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
fname VARCHAR(20),
iname VARCHAR(20),
oname VARCHAR(20),
posada VARCHAR(20),
oklad SMALLINT UNSIGNED,
semya_deti VARCHAR(20),
chlen_profsouza ENUM('+'),
CONSTRAINT pk_rabotniki PRIMARY KEY (man_id)
);
Query OK, 0 rows affected (0.14 sec)

CREATE TABLE everyday
(day TIMESTAMP,
day_id SMALLINT UNSIGNED,
bolen ENUM('+'),
razmer_premii SMALLINT UNSIGNED,
CONSTRAINT fk_man_id FOREIGN KEY (day_id)
REFERENCES rabotniki (man_id)
);
Query OK, 0 rows affected (0.67 sec)

CREATE TABLE everymonth
(month_id SMALLINT UNSIGNED,
day TIMESTAMP,
month_dohod SMALLINT UNSIGNED,
CONSTRAINT fk_man_id2 FOREIGN KEY (month_id)
REFERENCES rabotniki (man_id)
);
Query OK, 0 rows affected (0.67 sec)

DELIMITER //
CREATE TRIGGER dohod 
AFTER INSERT ON everyday
FOR EACH ROW
BEGIN
IF new.bolen is not null and (select chlen_profsouza from rabotniki where man_id = NEW.day_id) is null then
INSERT INTO everymonth
(month_id, month_dohod) VALUES (NEW.day_id, (((select razmer_premii from everyday where NEW.day_id) + (select oklad from rabotniki where man_id = NEW.day_id))/2));
else
INSERT INTO everymonth
(month_id, month_dohod) VALUES (NEW.day_id, ((select razmer_premii from everyday where NEW.day_id) + (select oklad from rabotniki where man_id = NEW.day_id)));
END IF;
END;
//

INSERT INTO rabotniki
(fname, iname, oname, posada, oklad, semya_deti, chlen_profsouza) VALUES ('Волков', 'Валентин', 'Юрьевич', 'газосварщик', 2400, 'женат, детей нету', '+');
Query OK, 1 row affected (0.00 sec)

INSERT INTO rabotniki
(fname, iname, oname, posada, oklad, semya_deti) VALUES ('Хворост', 'Алексей', 'Сергеевич', 'водитель-каптёрщик', 1750, 'женат, детей есть');
Query OK, 1 row affected (0.00 sec)

INSERT INTO rabotniki
(fname, iname, oname, posada, oklad, semya_deti) VALUES ('Мельник', 'Вадим', 'Генадиевич', 'токарь', 1500, 'не женат, детей нету');
Query OK, 1 row affected (0.00 sec)

INSERT INTO everyday
(day_id, razmer_premii) VALUES (1, 200);
Query OK, 1 row affected (0.00 sec)

INSERT INTO everyday
(day_id, razmer_premii) VALUES (2, 300);
ERROR 1242 (21000): Subquery returns more than 1 row

where NEW.day_id

where day_id = NEW.day_id

mysql> INSERT INTO everyday
    -> (day_id, razmer_premii) VALUES (1, 200);
    -> //
Query OK, 1 row affected (0.08 sec)

mysql> INSERT INTO everyday
    -> (day_id, bolen, razmer_premii) VALUES (1, '+', 150);
    -> //
ERROR 1242 (21000): Subquery returns more than 1 row

select razmer_premii from everyday where day_id = 1

select oklad from rabotniki where man_id = 1

INSERT INTO everymonth
(month_id, month_dohod)
 VALUES 
(NEW.day_id, (((select razmer_premii from everyday where NEW.day_id) + (select oklad from rabotniki where man_id = NEW.day_id))/2)); /*4 закрыв скобки*/
else
INSERT INTO everymonth
(month_id, month_dohod) 
VALUES 
(NEW.day_id, ((select razmer_premii from everyday where NEW.day_id) + (select oklad from rabotniki where man_id = NEW.day_id))); /*3 закрыв скобки*/
END IF;

DELIMITER //
CREATE TRIGGER dohod 
AFTER INSERT ON everyday
FOR EACH ROW
BEGIN
IF new.bolen is not null and (select chlen_profsouza from rabotniki where man_id = NEW.day_id) is null then
INSERT INTO everymonth
(month_id, month_dohod) VALUES (NEW.day_id, ((select razmer_premii from everyday where day_id = NEW.day_id) + (select oklad from rabotniki where man_id = NEW.day_id))/2);
else
INSERT INTO everymonth
(month_id, month_dohod) VALUES (NEW.day_id, ((select razmer_premii from everyday where day_id = NEW.day_id) + (select oklad from rabotniki where man_id = NEW.day_id)));
END IF;
END;
//

select SUMM(month_dohod) - SUMM(month_dohod*13/100) from everymonth where month_id = 1;

select razmer_premii from everyday where day_id = NEW.day_id;

(NEW.day_id, ((select razmer_premii from everyday where NEW.day_id = month_id) + (select oklad from rabotniki where man_id = NEW.day_id)));

select razmer_premii from everyday where day_id = NEW.day_id = day_id;



(NEW.day_id, ((select razmer_premii from everyday where NEW.day_id) + (select oklad from rabotniki where NEW.day_id)));