Revert "Merge pull request #13344 from ccutrer/fix-from-default-select"

This reverts commit 3ea840355409dc205a9e0d027fc09f1452636969, reversing
changes made to e4cde5d58cbb09d1843796f96ba86225ff94fe05.

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/lib/active_record/relation/query_methods.rb

Reason: using `from` without `select` should not change the select list
to SELECT * because it can lead different query results. If it is needed
to change the table to a subquery or a view you can pass a table alias
in the `from` call or use `select('subquery.*')`.

Fixes #14049.

3 files changed, 6 insertions, 21 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index e49a0f1323..458b9d77c2 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -533,22 +533,6 @@
 
     *Damien Mathieu*
 
-*   Improve the default select when `from` is used.
-
-    Previously, if you did something like Topic.from(:temp_topics), it
-    would generate SQL like:
-
-        SELECT topics.* FROM temp_topics;
-
-    Which is will cause an error since there's not a topics table to select
-    from.
-
-    Now the default if you use from is just `*`:
-
-        SELECT * FROM temp_topics;
-
-    *Cody Cutrer*
-
 *   Fix `PostgreSQL` insert to properly extract table name from multiline string SQL.
 
     Previously, executing an insert SQL in `PostgreSQL` with a command like this:
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index e2a1af7342..5d38f0dce8 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -995,8 +995,6 @@ module ActiveRecord
           columns_hash.key?(field.to_s) ? arel_table[field] : field
         end
         arel.project(*expanded_select)
-      elsif from_value
-        arel.project(Arel.star)
       else
         arel.project(@klass.arel_table[Arel.star])
       end
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index e390d37871..8718110c36 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -151,11 +151,14 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal relation.to_a, Comment.select('a.*').from(relation, :a).to_a
   end
 
-  def test_finding_with_subquery_without_select
-    relation = Topic.where(:approved => true)
-    assert_equal relation.to_a, Topic.from(relation).to_a
+  def test_finding_with_subquery_without_select_does_not_change_the_select
+    relation = Topic.where(approved: true)
+    assert_raises(ActiveRecord::StatementInvalid) do
+      Topic.from(relation).to_a
+    end
   end
 
+
   def test_finding_with_conditions
     assert_equal ["David"], Author.where(:name => 'David').map(&:name)
     assert_equal ['Mary'],  Author.where(["name = ?", 'Mary']).map(&:name)