FROM subquery should work if order provided (#1151)

Author: aidanharan

CHANGELOG.md

@@ -1,3 +1,9 @@
+## Unreleased
+
+#### Fixed
+
+- [#1151](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/1151) FROM subquery should work if order provided
+
 ## v7.1.1
 
 #### Fixed

lib/arel/visitors/sqlserver.rb

@@ -213,7 +213,7 @@ def visit_Arel_Nodes_SelectStatement_SQLServer_Lock(collector, options = {})
 
       def visit_Orders_And_Let_Fetch_Happen(o, collector)
         make_Fetch_Possible_And_Deterministic o
-        unless o.orders.empty?
+        if o.orders.any?
           collector << " ORDER BY "
           len = o.orders.length - 1
           o.orders.each_with_index { |x, i|
@@ -261,15 +261,14 @@ def select_statement_lock?
 
       def make_Fetch_Possible_And_Deterministic(o)
         return if o.limit.nil? && o.offset.nil?
+        return if o.orders.any?
 
         t = table_From_Statement o
         pk = primary_Key_From_Table t
         return unless pk
 
-        if o.orders.empty?
-          # Prefer deterministic vs a simple `(SELECT NULL)` expr.
-          o.orders = [pk.asc]
-        end
+        # Prefer deterministic vs a simple `(SELECT NULL)` expr.
+        o.orders = [pk.asc]
       end
 
       def distinct_One_As_One_Is_So_Not_Fetch(o)

test/cases/fetch_test_sqlserver.rb

@@ -42,6 +42,25 @@ class FetchTestSqlserver < ActiveRecord::TestCase
     end
   end
 
+  describe "FROM subquery" do
+    let(:from_sql) { "(SELECT [books].* FROM [books]) [books]" }
+
+    it "SQL generated correctly for FROM subquery if order provided" do
+      query = Book.from(from_sql).order(:id).limit(5)
+
+      assert_equal query.to_sql, "SELECT [books].* FROM (SELECT [books].* FROM [books]) [books] ORDER BY [books].[id] ASC OFFSET 0 ROWS FETCH NEXT 5 ROWS ONLY"
+      assert_equal query.to_a.count, 5
+    end
+
+    it "exception thrown if FROM subquery is provided without an order" do
+      query = Book.from(from_sql).limit(5)
+
+      assert_raise(ActiveRecord::StatementInvalid) do
+        query.to_sql
+      end
+    end
+  end
+
   protected
 
   def create_10_books