CODEWITHSUNDEEP
mysql
user813801
user813801

Reputation: 521

Sum Two Columns in Two Mysql Tables

I've been searching everywhere for this but no cigar. Smoke is starting to come out of my ears. please help

How do you sum two columns in two tables and group by userid?

Have two tables.

Recipe Table
recipeid   userid   recipe_num_views

Meals Table
mealsid   userid    meal_num_views

Goal is to sum the num views in both tables and group by userid

so for example
Recipe Table
1    3     4
2    4     6

Meal Table
1    3     2
2    4     5


select sum(recipe views)+sum(meal views) 
WHERE recipe.userid=meals.userid GROUP BY userid

should give 

userid=3 , sum=6
userid=4, sum=11

this gives a much bigger number.

Upvotes: 13

Views: 64766

Answers (2)

manji
manji

Reputation: 47968

SELECT recipe.userid, sum(recipe_num_views+meal_num_views) 
FROM Recipe JOIN Meals ON recipe.userid=meals.userid
GROUP BY recipe.userid

EDIT:

OK, from your comments, I understand that when you have for user 3: 4 recipes & 3 meals you will get the sum of the combination of all these rows => sum(recipes)*3 + sum(meals)*4

Try this query instead:

select r.userid, (sum_recipe + sum_meal) sum_all
FROM
(select userid, sum(recipe_num_views) sum_recipe
FROM Recipe
GROUP BY userid) r
JOIN (
select userid, sum(meal_num_views) sum_meal
FROM Meals
GROUP BY userid) m ON r.userid = m.userid

Upvotes: 14

Johan
Johan

Reputation: 76753

If you're selecting from 2 tables you need to join them. Otherwise MySQL will not know how to link up the two tables.

select sum(recipe_num_views + meal_num_views) 
from recipe r
inner join meals m ON (r.user_id = m.user_id)
group by m.user_id

See:
http://dev.mysql.com/doc/refman/5.5/en/join.html
http://www.codinghorror.com/blog/2007/10/a-visual-explanation-of-sql-joins.html

Upvotes: 2

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