1 files changed, 10 insertions, 14 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 61bac6741f..c29692d6ca 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -63,7 +63,7 @@ module ActiveRecord
 
       def column_spec_for_primary_key(column)
         spec = {}
-        if column.extra == 'auto_increment'
+        if column.auto_increment?
           return unless column.limit == 8
           spec[:id] = ':bigint'
         else
@@ -103,6 +103,10 @@ module ActiveRecord
           collation && !collation.match(/_ci$/)
         end
 
+        def auto_increment?
+          extra == 'auto_increment'
+        end
+
         private
 
         # MySQL misreports NOT NULL column default when none is given.
@@ -808,7 +812,7 @@ module ActiveRecord
         options = {
           default: column.default,
           null: column.null,
-          auto_increment: column.extra == "auto_increment"
+          auto_increment: column.auto_increment?
         }
 
         current_type = select_one("SHOW COLUMNS FROM #{quote_table_name(table_name)} LIKE '#{column_name}'", 'SCHEMA')["Type"]
@@ -913,18 +917,10 @@ module ActiveRecord
       end
 
       class MysqlDateTime < Type::DateTime # :nodoc:
-        def type_cast_for_database(value)
-          if value.acts_like?(:time) && value.respond_to?(:usec)
-            result = super.to_s(:db)
-            case precision
-            when 1..6
-              "#{result}.#{sprintf("%0#{precision}d", value.usec / 10 ** (6 - precision))}"
-            else
-              result
-            end
-          else
-            super
-          end
+        private
+
+        def has_precision?
+          precision || 0
         end
       end