SQL (postgres) to ActiveRecord Query

Question

I'm having a hard time converting this SQL query to ActiveRecord. Here's my SQL.

SELECT distinct stc_term_gpa,
    user_id,
    lesley_id,
    first,
    last,
FROM lesley_grades
ORDER BY user_id

and this returns 437 rows - which is want I want. I have no problems runnings this in SQL

But when I try to run this in Rails in the Console:

LesleyGrade.select(:stc_term_gpa, :user_id, :lesley_id, :first, :last).distinct.order(:user_id)

I verified the count in rails

LesleyGrade.select(:stc_term_gpa, :user_id, :lesley_id, :first, :last).distinct.order(:user_id).count(:all)

I return 1440 rows - which is not what I want...that's all the data rows in my DB.

What's going on?

UPDATE

This is strange:

When I run the active record query in Rails Console and get the count 1440

LesleyGrade.select(:stc_term_gpa, :user_id, :lesley_id, :first, :last).distinct.order(:user_id).count(:all)

I check the SQL in the console (the one that ActiveRecord produces) and this is what it produces:

SELECT DISTINCT 
    "lesley_grades"."stc_term_gpa", 
    "lesley_grades"."user_id", 
    "lesley_grades"."lesley_id", 
    "lesley_grades"."first", 
    "lesley_grades"."last" 
FROM "lesley_grades"   
ORDER BY "lesley_grades"."user_id" ASC

When I run the above SQL in a SQL client I get the 437 rows. Again a discrepancy.

HOWEVER when I'm playing with the SQL that rails produces, and take the above statement and add in lesley_grades.id in the projection on my own accord and running raw SQL in a client like this, I get 1440 row (shouldn't it still be getting 437 even if I place the ID there?)

SELECT DISTINCT 
    "lesley_grades"."stc_term_gpa", 
   **"lesley_grades"."id"**, 
    "lesley_grades"."user_id", 
    "lesley_grades"."lesley_id", 
    "lesley_grades"."first", 
    "lesley_grades"."last"
FROM "lesley_grades"
ORDER BY "lesley_grades"."user_id" ASC

So I guess the question is does ActiveRecord some how use the ID for something in the a query sneakily, which is why I'm receiving 1440? How do I get my distinct 437 rows?

Answer 1

You can still use find_by_sql metod

query = "SELECT distinct stc_term_gpa, user_id,lesley_id,first,last
         FROM lesley_grades
         ORDER BY user_id"
expectedResult = LesleyGrade.find_by_sql(query)