Rails Mysql2::Error: Operand should contain 1 column(s)

Question

I wanted to take this method:

self.spend_on_scholarships_for_african_people = training_programs.scholarships.joins(:participants).where('participants.race' => AFRICAN_RACES).sum('participants.spend')

and now want break it into different genders. We capture gender within the participants table. so i tried using active records array conditions within the query to do so like this:

self.bursary_spend_on_potential_female_employees = training_programs.scholarships.joins(:participants).where('participants.race = ? AND participants.gender = ?', AFRICAN_RACES, 'Female').sum('participants.spend')
self.bursary_spend_on_potential_male_employees = training_programs.scholarships.joins(:participants).where('participants.race = ? AND participants.gender = ?', AFRICAN_RACES, 'Male').sum('participants.spend')

But i keep getting the following error:

ActiveRecord::StatementInvalid - Mysql2::Error: Operand should contain 1 column(s): SELECT SUM(participants.spend) AS sum_id FROM `training_programs` INNER JOIN `participants` ON `participants`.`training_program_id` = `training_programs`.`id` WHERE `training_programs`.`skills_development_id` IS NULL AND `training_programs`.`skills_development_type` = 'SkillsDevelopment' AND `training_programs`.`scholarship` = 1 AND (participants.race = 'African','Coloured','Indian' AND participants.gender = 'Female'):

I have cut up my query and i can't seem to find what i have done wrong?

zwippie · Accepted Answer · 2014-06-10 08:57:35Z

6

participants.race = 'African','Coloured','Indian'

should be

participants.race IN ('African','Coloured','Indian')

To get that SQL result, change the way you build your query to something like:

participants.race IN (?)

answered Jun 10, 2014 at 8:57

zwippie

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1 Comment

legendary_rob Over a year ago

zwippie you legend you!! it wasnt looking at it like an array. i was confused since it was working fine in the first instance. thank you so much!

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