3 files changed, 18 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
index e8358271ab..083cd6340f 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
@@ -25,6 +25,14 @@ module ActiveRecord
           end
 
           def add_column_options!(sql, options)
+            # By default, TIMESTAMP columns are NOT NULL, cannot contain NULL values,
+            # and assigning NULL assigns the current timestamp. To permit a TIMESTAMP
+            # column to contain NULL, explicitly declare it with the NULL attribute.
+            # See http://dev.mysql.com/doc/refman/5.7/en/timestamp-initialization.html
+            if /\Atimestamp\b/.match?(options[:column].sql_type) && !options[:primary_key]
+              sql << " NULL" unless options[:null] == false || options_include_default?(options)
+            end
+
             if charset = options[:charset]
               sql << " CHARACTER SET #{charset}"
             end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
index 773bbcef4e..6d88c14d50 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
@@ -75,6 +75,11 @@ module ActiveRecord
 
           super
         end
+
+        private
+          def aliased_types(name, fallback)
+            fallback
+          end
       end
 
       class Table < ActiveRecord::ConnectionAdapters::Table
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
index ad4a069d73..3e0afd9761 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
@@ -30,7 +30,10 @@ module ActiveRecord
           end
 
           def schema_type(column)
-            if column.sql_type == "tinyblob"
+            case column.sql_type
+            when /\Atimestamp\b/
+              :timestamp
+            when "tinyblob"
               :blob
             else
               super
@@ -38,7 +41,7 @@ module ActiveRecord
           end
 
           def schema_precision(column)
-            super unless /time/.match?(column.sql_type) && column.precision == 0
+            super unless /\A(?:date)?time(?:stamp)?\b/.match?(column.sql_type) && column.precision == 0
           end
 
           def schema_collation(column)