From c57ab31fd734477eaf0e4781fdfd4150d2a26de4 Mon Sep 17 00:00:00 2001
From: Aidan Haran <aidanharan@yahoo.com>
Date: Thu, 27 Feb 2020 11:34:31 +0000
Subject: [PATCH] Order by selected items when using distinct exists

---
 .../sqlserver/core_ext/finder_methods.rb      | 43 +++++++++++++++++++
 .../connection_adapters/sqlserver_adapter.rb  |  1 +
 2 files changed, 44 insertions(+)
 create mode 100644 lib/active_record/connection_adapters/sqlserver/core_ext/finder_methods.rb

diff --git a/lib/active_record/connection_adapters/sqlserver/core_ext/finder_methods.rb b/lib/active_record/connection_adapters/sqlserver/core_ext/finder_methods.rb
new file mode 100644
index 000000000..fc9ff9db3
--- /dev/null
+++ b/lib/active_record/connection_adapters/sqlserver/core_ext/finder_methods.rb
@@ -0,0 +1,43 @@
+require 'active_record/relation'
+require 'active_record/version'
+
+module ActiveRecord
+  module ConnectionAdapters
+    module SQLServer
+      module CoreExt
+        module FinderMethods
+
+          private
+
+          # Same as original except we order by values in distinct select if present.
+          def construct_relation_for_exists(conditions)
+            if distinct_value && offset_value
+              relation = limit!(1)
+
+              if select_values.present?
+                relation = relation.order(*select_values)
+              else
+                relation = relation.except(:order)
+              end
+            else
+              relation = except(:select, :distinct, :order)._select!(::ActiveRecord::FinderMethods::ONE_AS_ONE).limit!(1)
+            end
+
+            case conditions
+            when Array, Hash
+              relation.where!(conditions) unless conditions.empty?
+            else
+              relation.where!(primary_key => conditions) unless conditions == :none
+            end
+
+            relation
+          end
+        end
+      end
+    end
+  end
+end
+
+ActiveSupport.on_load(:active_record) do
+  ActiveRecord::Relation.include(ActiveRecord::ConnectionAdapters::SQLServer::CoreExt::FinderMethods)
+end
diff --git a/lib/active_record/connection_adapters/sqlserver_adapter.rb b/lib/active_record/connection_adapters/sqlserver_adapter.rb
index b3f745ac6..cc8564320 100644
--- a/lib/active_record/connection_adapters/sqlserver_adapter.rb
+++ b/lib/active_record/connection_adapters/sqlserver_adapter.rb
@@ -7,6 +7,7 @@
 require 'active_record/connection_adapters/sqlserver/core_ext/explain'
 require 'active_record/connection_adapters/sqlserver/core_ext/explain_subscriber'
 require 'active_record/connection_adapters/sqlserver/core_ext/attribute_methods'
+require 'active_record/connection_adapters/sqlserver/core_ext/finder_methods'
 require 'active_record/connection_adapters/sqlserver/version'
 require 'active_record/connection_adapters/sqlserver/type'
 require 'active_record/connection_adapters/sqlserver/database_limits'