Rails 6.1: Coerce test as SQL is invalid for MSSQL

[aidanharan]

Coercing the FinderTest#test_include_on_unloaded_relation_with_having_referencing_aliased_select test as SQL Server does not support the SQL.

There is no point re-implementing the coerced test as its purpose is to test the HAVING clause referencing an aliased SELECT.

SQL Server

Author.select("COUNT(*) as total_posts", "authors.*").joins(:posts).group(:id).having("total_posts > 2").include?(bob)

SQL generated:

SELECT COUNT(*) as total_posts, authors.*
FROM [authors] 
INNER JOIN [posts] ON [posts].[author_id] = [authors].[id] 
GROUP BY [authors].[id] 
HAVING (total_posts > 2)

This SQL is invalid in SQL Server and throws the error Invalid column name 'total_posts'. There are 2 reasons why the SQL is invalid:

• Cannot use SELECT alias total_posts in HAVING clause.
• Cannot SELECT authors.* as the columns are not in the GROUP clause.

PostgreSQL
PostgreSQL skips this test (https://github.com/rails/rails/blob/d927db7eec984a980e5533dc307164e24c137690/activerecord/test/cases/finder_test.rb#L428) as it does not support the SQL.

SELECT COUNT(*) as total_posts, authors.* 
FROM "authors" 
INNER JOIN "posts" ON "posts"."author_id" = "authors"."id" 
GROUP BY "authors"."id" 
HAVING (total_posts > 2)

Error:

ActiveRecord::StatementInvalid: PG::UndefinedColumn: ERROR:  column "total_posts" does not exist
LINE 1: ... = "authors"."id" GROUP BY "authors"."id" HAVING (total_post...

MySQL
Generates the following SQL which is valid in MySQL.

SELECT COUNT(*) as total_posts, authors.* 
FROM `authors` 
INNER JOIN `posts` ON `posts`.`author_id` = `authors`.`id` 
GROUP BY `authors`.`id` 
HAVING (total_posts > 2)

SQLite
Generates the following SQL which is valid in SQLite.

SELECT COUNT(*) as total_posts, authors.* 
FROM "authors" 
INNER JOIN "posts" ON "posts"."author_id" = "authors"."id" 
GROUP BY "authors"."id" 
HAVING (total_posts > 2)