3 files changed, 14 insertions, 1 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 70d281b62b..5479ddab71 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -627,6 +627,7 @@ module ActiveRecord
         ER_LOCK_WAIT_TIMEOUT    = 1205
         ER_QUERY_INTERRUPTED    = 1317
         ER_QUERY_TIMEOUT        = 3024
+        ER_FK_INCOMPATIBLE_COLUMNS = 3780
 
         def translate_exception(exception, message:, sql:, binds:)
           case error_number(exception)
@@ -634,7 +635,7 @@ module ActiveRecord
             RecordNotUnique.new(message, sql: sql, binds: binds)
           when ER_NO_REFERENCED_ROW, ER_ROW_IS_REFERENCED, ER_ROW_IS_REFERENCED_2, ER_NO_REFERENCED_ROW_2
             InvalidForeignKey.new(message, sql: sql, binds: binds)
-          when ER_CANNOT_ADD_FOREIGN
+          when ER_CANNOT_ADD_FOREIGN, ER_FK_INCOMPATIBLE_COLUMNS
             mismatched_foreign_key(message, sql: sql, binds: binds)
           when ER_CANNOT_CREATE_TABLE
             if message.include?("errno: 150")
diff --git a/activerecord/lib/arel/nodes/case.rb b/activerecord/lib/arel/nodes/case.rb
index 654a54825e..b8f83128c8 100644
--- a/activerecord/lib/arel/nodes/case.rb
+++ b/activerecord/lib/arel/nodes/case.rb
@@ -3,6 +3,8 @@
 module Arel # :nodoc: all
   module Nodes
     class Case < Arel::Nodes::Node
+      include Arel::AliasPredication
+
       attr_accessor :case, :conditions, :default
 
       def initialize(expression = nil, default = nil)
diff --git a/activerecord/test/cases/arel/nodes/case_test.rb b/activerecord/test/cases/arel/nodes/case_test.rb
index 89861488df..946c2b0453 100644
--- a/activerecord/test/cases/arel/nodes/case_test.rb
+++ b/activerecord/test/cases/arel/nodes/case_test.rb
@@ -80,6 +80,16 @@ module Arel
             assert_equal 2, array.uniq.size
           end
         end
+
+        describe "#as" do
+          it "allows aliasing" do
+            node = Case.new "foo"
+            as = node.as("bar")
+
+            assert_equal node, as.left
+            assert_kind_of Arel::Nodes::SqlLiteral, as.right
+          end
+        end
       end
     end
   end