1 files changed, 29 insertions, 38 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 d098ded77c..138ab811dc 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -3,18 +3,29 @@ require 'arel/visitors/bind_visitor'
 module ActiveRecord
   module ConnectionAdapters
     class AbstractMysqlAdapter < AbstractAdapter
+      include Savepoints
+
       class SchemaCreation < AbstractAdapter::SchemaCreation
-        private
 
         def visit_AddColumn(o)
-          add_column_position!(super, o)
+          add_column_position!(super, column_options(o))
         end
 
-        def add_column_position!(sql, column)
-          if column.first
+        private
+        def visit_ChangeColumnDefinition(o)
+          column = o.column
+          options = o.options
+          sql_type = type_to_sql(o.type, options[:limit], options[:precision], options[:scale])
+          change_column_sql = "CHANGE #{quote_column_name(column.name)} #{quote_column_name(options[:name])} #{sql_type}"
+          add_column_options!(change_column_sql, options)
+          add_column_position!(change_column_sql, options)
+        end
+
+        def add_column_position!(sql, options)
+          if options[:first]
             sql << " FIRST"
-          elsif column.after
-            sql << " AFTER #{quote_column_name(column.after)}"
+          elsif options[:after]
+            sql << " AFTER #{quote_column_name(options[:after])}"
           end
           sql
         end
@@ -165,6 +176,7 @@ module ActiveRecord
         @quoted_column_names, @quoted_table_names = {}, {}
 
         if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
+          @prepared_statements = true
           @visitor = Arel::Visitors::MySQL.new self
         else
           @visitor = unprepared_visitor
@@ -184,11 +196,6 @@ module ActiveRecord
         true
       end
 
-      # Returns true, since this connection adapter supports savepoints.
-      def supports_savepoints?
-        true
-      end
-
       def supports_bulk_alter? #:nodoc:
         true
       end
@@ -237,8 +244,8 @@ module ActiveRecord
       # QUOTING ==================================================
 
       def quote(value, column = nil)
-        if value.kind_of?(String) && column && column.type == :binary && column.class.respond_to?(:string_to_binary)
-          s = column.class.string_to_binary(value).unpack("H*")[0]
+        if value.kind_of?(String) && column && column.type == :binary
+          s = value.unpack("H*")[0]
           "x'#{s}'"
         elsif value.kind_of?(BigDecimal)
           value.to_s("F")
@@ -330,18 +337,6 @@ module ActiveRecord
         # Transactions aren't supported
       end
 
-      def create_savepoint
-        execute("SAVEPOINT #{current_savepoint_name}")
-      end
-
-      def rollback_to_savepoint
-        execute("ROLLBACK TO SAVEPOINT #{current_savepoint_name}")
-      end
-
-      def release_savepoint
-        execute("RELEASE SAVEPOINT #{current_savepoint_name}")
-      end
-
       # In the simple case, MySQL allows us to place JOINs directly into the UPDATE
       # query. However, this does not allow for LIMIT, OFFSET and ORDER. To support
       # these, we must use a subquery.
@@ -460,7 +455,8 @@ module ActiveRecord
         sql = "SHOW FULL FIELDS FROM #{quote_table_name(table_name)}"
         execute_and_free(sql, 'SCHEMA') do |result|
           each_hash(result).map do |field|
-            new_column(field[:Field], field[:Default], field[:Type], field[:Null] == "YES", field[:Collation], field[:Extra])
+            field_name = set_field_encoding(field[:Field])
+            new_column(field_name, field[:Default], field[:Type], field[:Null] == "YES", field[:Collation], field[:Extra])
           end
         end
       end
@@ -661,10 +657,9 @@ module ActiveRecord
       end
 
       def add_column_sql(table_name, column_name, type, options = {})
-        add_column_sql = "ADD #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
-        add_column_options!(add_column_sql, options)
-        add_column_position!(add_column_sql, options)
-        add_column_sql
+        td = create_table_definition table_name, options[:temporary], options[:options]
+        cd = td.new_column_definition(column_name, type, options)
+        schema_creation.visit_AddColumn cd
       end
 
       def change_column_sql(table_name, column_name, type, options = {})
@@ -678,14 +673,12 @@ module ActiveRecord
           options[:null] = column.null
         end
 
-        change_column_sql = "CHANGE #{quote_column_name(column_name)} #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
-        add_column_options!(change_column_sql, options)
-        add_column_position!(change_column_sql, options)
-        change_column_sql
+        options[:name] = column.name
+        schema_creation.accept ChangeColumnDefinition.new column, type, options
       end
 
       def rename_column_sql(table_name, column_name, new_column_name)
-        options = {}
+        options = { name: new_column_name }
 
         if column = columns(table_name).find { |c| c.name == column_name.to_s }
           options[:default] = column.default
@@ -696,9 +689,7 @@ module ActiveRecord
         end
 
         current_type = select_one("SHOW COLUMNS FROM #{quote_table_name(table_name)} LIKE '#{column_name}'", 'SCHEMA')["Type"]
-        rename_column_sql = "CHANGE #{quote_column_name(column_name)} #{quote_column_name(new_column_name)} #{current_type}"
-        add_column_options!(rename_column_sql, options)
-        rename_column_sql
+        schema_creation.accept ChangeColumnDefinition.new column, current_type, options
       end
 
       def remove_column_sql(table_name, column_name, type = nil, options = {})