From 242c7e8b6602f4e6e5e73ea2d6f23363ece32bd4 Mon Sep 17 00:00:00 2001
From: Yasuo Honda <yasuo.honda@gmail.com>
Date: Thu, 19 Nov 2020 18:38:53 +0900
Subject: [PATCH] Merge pull request #2070 from
 koic/build_subselect_doesnt_have_ordering

`build_subselect` does not have ordering
---
 lib/arel/visitors/oracle.rb                   | 11 ++++++
 lib/arel/visitors/oracle12.rb                 | 11 ++++++
 .../oracle_enhanced_adapter_spec.rb           | 39 +++++++++++++++++++
 3 files changed, 61 insertions(+)

diff --git a/lib/arel/visitors/oracle.rb b/lib/arel/visitors/oracle.rb
index 573ec8240..7a5b1179a 100644
--- a/lib/arel/visitors/oracle.rb
+++ b/lib/arel/visitors/oracle.rb
@@ -248,6 +248,17 @@ def is_distinct_from(o, collector)
           collector = visit [o.left, o.right, 0, 1], collector
           collector << ")"
         end
+
+        # Oracle will occur an error `ORA-00907: missing right parenthesis`
+        # when using `ORDER BY` in `UPDATE` or `DELETE`'s subquery.
+        #
+        # This method has been overridden based on the following code.
+        # https://github.com/rails/rails/blob/v6.1.0.rc1/activerecord/lib/arel/visitors/to_sql.rb#L815-L825
+        def build_subselect(key, o)
+          stmt             = super
+          stmt.orders      = [] # `orders` will never be set to prevent `ORA-00907`.
+          stmt
+        end
     end
   end
 end
diff --git a/lib/arel/visitors/oracle12.rb b/lib/arel/visitors/oracle12.rb
index 55c96610a..443772372 100644
--- a/lib/arel/visitors/oracle12.rb
+++ b/lib/arel/visitors/oracle12.rb
@@ -155,6 +155,17 @@ def is_distinct_from(o, collector)
           collector = visit [o.left, o.right, 0, 1], collector
           collector << ")"
         end
+
+        # Oracle will occur an error `ORA-00907: missing right parenthesis`
+        # when using `ORDER BY` in `UPDATE` or `DELETE`'s subquery.
+        #
+        # This method has been overridden based on the following code.
+        # https://github.com/rails/rails/blob/v6.1.0.rc1/activerecord/lib/arel/visitors/to_sql.rb#L815-L825
+        def build_subselect(key, o)
+          stmt             = super
+          stmt.orders      = [] # `orders` will never be set to prevent `ORA-00907`.
+          stmt
+        end
     end
   end
 end
diff --git a/spec/active_record/connection_adapters/oracle_enhanced_adapter_spec.rb b/spec/active_record/connection_adapters/oracle_enhanced_adapter_spec.rb
index e5ddeb974..10933c05e 100644
--- a/spec/active_record/connection_adapters/oracle_enhanced_adapter_spec.rb
+++ b/spec/active_record/connection_adapters/oracle_enhanced_adapter_spec.rb
@@ -150,6 +150,45 @@ class ::TestEmployee2 < ActiveRecord::Base
     end
   end
 
+  describe "`has_many` assoc has `dependent: :delete_all` with `order`" do
+    before(:all) do
+      schema_define do
+        create_table :test_posts do |t|
+          t.string      :title
+        end
+        create_table :test_comments do |t|
+          t.integer     :test_post_id
+          t.string      :description
+        end
+        add_index :test_comments, :test_post_id
+      end
+      class ::TestPost < ActiveRecord::Base
+        has_many :test_comments, -> { order(:id) }, dependent: :delete_all
+      end
+      class ::TestComment < ActiveRecord::Base
+        belongs_to :test_post
+      end
+      TestPost.transaction do
+        post = TestPost.create!(title: "Title")
+        TestComment.create!(test_post_id: post.id, description: "Description")
+      end
+    end
+
+    after(:all) do
+      schema_define do
+        drop_table :test_comments
+        drop_table :test_posts
+      end
+      Object.send(:remove_const, "TestPost")
+      Object.send(:remove_const, "TestComment")
+      ActiveRecord::Base.clear_cache!
+    end
+
+    it "should not occur `ActiveRecord::StatementInvalid: OCIError: ORA-00907: missing right parenthesis`" do
+      expect { TestPost.first.destroy }.not_to raise_error
+    end
+  end
+
   describe "eager loading" do
     before(:all) do
       schema_define do