Updating a table column with multi table conditions - mysql

Question

I am trying to create a procedure that will update all fruits status if a fruit has at least one critical attribute.
For example i have an apple,banana and an orange with many attributes. One of the attributes of apple, orange marked as "Yes" on critical. in that case with a single call of the procedure apple and orange will have status id pointing on "bad", and banana as "good".
create table `status` (
s_id int,
s_stat enum ("Bad", "Good", "Rotten"),
primary key (s_id)
) ENGINE = InnoDB;
create table fruits (
f_id int,
f_name varchar(10),
f_status int,
primary key (f_id),
foreign key (f_status) references `status`(s_id)
on update cascade
) ENGINE = InnoDB;
create table attributes (
a_id int,
a_description varChar(25),
a_critital enum ("Yes", "No"),
primary key(a_id)
) ENGINE = InnoDB;
create table fruits_attributes (
fa_f_id int,
fa_a_id int,
primary key(fa_f_id, fa_a_id),
foreign key (fa_f_id) references fruits(f_id)
on update cascade,
foreign key (fa_a_id) references attributes(a_id)
on update cascade
) ENGINE = InnoDB;
insert into `status` values
(1, "Bad"),
(2, "Good"),
(3, "Rotten")
;
insert into fruits values
(1, "Apple", null),
(2, "Banana", null),
(3, "Orange", null)
;
insert into attributes values
(1, "Yellow mark", "No"),
(2, "Cuts", "Yes"),
(3, "Dirt", "No")
;
insert into fruits_attributes values
(1, 1),
(1, 2),
(1, 3),
(2, 3),
(3, 2)
;

Answer 1

So you are prioritising "Bad" over "Good". For example, if one apple is "Good", another apple is "Bad", you would update it as "Bad". Let me know if this is not the case.
For MySQL 8.0 version, db<>fiddle
CREATE PROCEDURE updtfruit()
BEGIN
UPDATE fruits f
JOIN (
SELECT f_id, s_id, ROW_NUMBER() OVER(PARTITION BY f_id ORDER BY s_id) AS rn
FROM fruits_attributes fa
JOIN fruits f ON fa.fa_f_id = f.f_id
JOIN attributes a ON fa.fa_a_id = a.a_id
JOIN `status` s ON s.s_stat = CASE WHEN a.a_critital = "Yes" THEN "Bad"
WHEN a.a_critital = "No" THEN "Good"
END
) filter ON f.f_id = filter.f_id
SET f.f_status = filter.s_id
WHERE filter.rn = 1;
END
For MySQL older versions, db<>fiddle
CREATE PROCEDURE updtfruit2()
BEGIN
UPDATE fruits f
JOIN (
SELECT f_id, MIN(s_id) AS s_id
FROM fruits_attributes fa
JOIN fruits f ON fa.fa_f_id = f.f_id
JOIN attributes a ON fa.fa_a_id = a.a_id
JOIN `status` s ON s.s_stat = CASE WHEN a.a_critital = "Yes" THEN "Bad"
WHEN a.a_critital = "No" THEN "Good"
END
GROUP BY f_id
) filter ON f.f_id = filter.f_id
SET f.f_status = filter.s_id;
END