easy_union_set

easily create unions and intersections in ActiveRecord.

Setup

gem 'easy_union_set'

Easy to use, So I'll jump straight into the examples

to create a UNION

Project.where("title LIKE '%a%'") | Project.having("LENGTH(description) > 10").group(:id)

# => SELECT "projects".* FROM ( SELECT "projects".* FROM "projects"  WHERE (title LIKE '%a%') UNION SELECT "projects".* FROM "projects"  GROUP BY id HAVING LENGTH(description) > 10 ) "projects"

to create an INTERSECT

Project.where("title LIKE '%a%'") & Project.having("LENGTH(description) > 10").group(:id)

# => SELECT "projects".* FROM ( SELECT "projects".* FROM "projects"  WHERE (title LIKE '%a%') INTERSECT SELECT "projects".* FROM "projects"  GROUP BY id HAVING LENGTH(description) > 10 ) "projects"

to create a UNION ALL

Project.where("title LIKE '%a%'") | {:all => Project.having("LENGTH(description) > 10").group(:id)}

# => SELECT "projects".* FROM ( SELECT "projects".* FROM "projects"  WHERE (title LIKE '%a%') UNION ALL SELECT "projects".* FROM "projects"  GROUP BY id HAVING LENGTH(description) > 10 ) "projects"

if for some reason you'd still rather make multiple queries and make a ruby union simply call #to_a on the AR:Relation object before using the #& or #| methods.