SQL case subquery + subquery > 0 - mysql

Question

i am trying to devide a number with another number. but because there is a chance that the result is 0 i want to make a case saying that if it is 0 then it should be 1 for this ive created this:
(CASE(SELECT COUNT(*)
FROM module_score
WHERE user_id = 40 AND medal_id > 1)
+
(SELECT COUNT(*)
FROM user_has_module_score uhms
WHERE user_id = 40 and medal_id > 1)> 0
THEN 1
ELSE 0 END) as passed_percentage
However i get the following syntax error:
medal_id > 1)> 0 THEN 1 ELSE 0 END) as passed_percentage
FROM system_learningbank.user U
WHERE U.id = 40 GROUP BY U.id
Error Code: 1064. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'THEN 1 ELSE 0 END) as passed_percentage FROM system_learningbank.user U WH' at line 7
So what is the right syntax if to validate that it is not 0? and in my above example i set the variable to 1 but that should be the actual count of the subqueries
My full sql statement
SELECT
(SELECT
COUNT(*)
FROM
module_score MS
WHERE
user_id = 40) + (SELECT
COUNT(UHMS.score)
FROM
user_has_module_score UHMS
WHERE
UHMS.user_id = 40) / ((SELECT
COUNT(*)
FROM
module_score
WHERE
user_id = 40 AND medal_id > 1) + (SELECT
COUNT(*)
FROM
user_has_module_score uhms
WHERE
user_id = 40 and medal_id > 1) > 0) as passed_percentageas
FROM
system_learningbank.user U
WHERE
U.id = 40
GROUP BY U.id;

Answer 1

You are missing the when:
(CASE WHEN (SELECT COUNT(*) FROM module_score WHERE user_id = 40 AND medal_id > 1) +
(SELECT COUNT(*) FROM user_has_module_score uhms WHERE user_id = 40 and medal_id > 1) > 0
THEN 1 ELSE 0
END) as passed_percentage
MySQL treats booleans as integers, so you can actually write this without the case:
( (SELECT COUNT(*) FROM module_score WHERE user_id = 40 AND medal_id > 1) +
(SELECT COUNT(*) FROM user_has_module_score uhms WHERE user_id = 40 and medal_id > 1) > 0
) as passed_percentage
EDIT:
SELECT (SELECT COUNT(*)
FROM module_score MS
WHERE user_id = 40
) +
(SELECT COUNT(UHMS.score)
FROM user_has_module_score UHMS
WHERE UHMS.user_id = 40
) / ((SELECT COUNT(*)
FROM module_score
WHERE user_id = 40 AND medal_id > 1
) +
(SELECT COUNT(*)
FROM user_has_module_score uhms
WHERE user_id = 40 and medal_id > 1
) > 0
) as passed_percentageas
FROM system_learningbank.user U
WHERE U.id = 40
GROUP BY U.id;
I suspect you want something more like this:
SELECT ((ms.cnt + hms.cnt) /
(case when ms.cnt_m1 + hms.cnt_m2 > 0 then ms.cnt_m1 + hms.cnt_m2 end)
) as passed_percentageas
FROM system_learningbank.user U left join
(select userid, count(*) as cnt, sum(medal_id > 1) as cnt_m1
from module_score
group by user_id
) ms
on ms.user_id = u.user_id left join
(select userid, count(*) as cnt, sum(medal_id > 1) as cnt_m1
from user_has_module_score
group by user_id
) hms
on hms.user_id = u.user_id
WHERE U.id = 40;
However, this still looks suspicious . . . the table names suggest that only one really codes the score you want, the denominator is more restrictive than the numerator, but this structure is basically what you seem to want.
GROUP BY U.id;