1 files changed, 49 insertions, 8 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
index cf68ddc2da..8af22fe9f5 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
@@ -5,6 +5,7 @@ require 'mysql2'
 
 module ActiveRecord
   class Base
+    # Establishes a connection to the database that's used by all Active Record objects.
     def self.mysql2_connection(config)
       config[:username] = 'root' if config[:username].nil?
 
@@ -132,6 +133,7 @@ module ActiveRecord
         ADAPTER_NAME
       end
 
+      # Returns true, since this connection adapter supports migrations.
       def supports_migrations?
         true
       end
@@ -140,6 +142,7 @@ module ActiveRecord
         true
       end
 
+      # Returns true, since this connection adapter supports savepoints.
       def supports_savepoints?
         true
       end
@@ -211,6 +214,8 @@ module ActiveRecord
         false
       end
 
+      # Disconnects from the database if already connected.
+      # Otherwise, this method does nothing.
       def disconnect!
         unless @connection.nil?
           @connection.close
@@ -290,6 +295,15 @@ module ActiveRecord
         execute sql.gsub('?') { quote(*binds.shift.reverse) }, name
       end
 
+      def exec_delete(sql, name, binds)
+        binds = binds.dup
+
+        # Pretend to support bind parameters
+        execute sql.gsub('?') { quote(*binds.shift.reverse) }, name
+        @connection.affected_rows
+      end
+      alias :exec_update :exec_delete
+
       def last_inserted_id(result)
         @connection.last_id
       end
@@ -357,6 +371,8 @@ module ActiveRecord
         end
       end
 
+      # Drops the database specified on the +name+ attribute
+      # and creates it again using the provided +options+.
       def recreate_database(name, options = {})
         drop_database(name)
         create_database(name, options)
@@ -377,6 +393,10 @@ module ActiveRecord
         end
       end
 
+      # Drops a MySQL database.
+      #
+      # Example:
+      #   drop_database('sebastian_development')
       def drop_database(name) #:nodoc:
         execute "DROP DATABASE IF EXISTS `#{name}`"
       end
@@ -395,22 +415,36 @@ module ActiveRecord
         show_variable 'collation_database'
       end
 
-      def tables(name = nil)
-        tables = []
-        execute("SHOW TABLES", name).each do |field|
-          tables << field.first
+      def tables(name = nil, database = nil) #:nodoc:
+        sql = ["SHOW TABLES", database].compact.join(' IN ')
+        execute(sql, 'SCHEMA').collect do |field|
+          field.first
         end
-        tables
+      end
+
+      def table_exists?(name)
+        return true if super
+
+        name          = name.to_s
+        schema, table = name.split('.', 2)
+
+        unless table # A table was provided without a schema
+          table  = schema
+          schema = nil
+        end
+
+        tables(nil, schema).include? table
       end
 
       def drop_table(table_name, options = {})
         super(table_name, options)
       end
 
+      # Returns an array of indexes for the given table.
       def indexes(table_name, name = nil)
         indexes = []
         current_index = nil
-        result = execute("SHOW KEYS FROM #{quote_table_name(table_name)}", name)
+        result = execute("SHOW KEYS FROM #{quote_table_name(table_name)}", 'SCHEMA')
         result.each(:symbolize_keys => true, :as => :hash) do |row|
           if current_index != row[:Key_name]
             next if row[:Key_name] == PRIMARY # skip the primary key
@@ -424,10 +458,11 @@ module ActiveRecord
         indexes
       end
 
+      # Returns an array of +Mysql2Column+ objects for the table specified by +table_name+.
       def columns(table_name, name = nil)
         sql = "SHOW FIELDS FROM #{quote_table_name(table_name)}"
         columns = []
-        result = execute(sql)
+        result = execute(sql, 'SCHEMA')
         result.each(:symbolize_keys => true, :as => :hash) { |field|
           columns << Mysql2Column.new(field[:Field], field[:Default], field[:Type], field[:Null] == "YES")
         }
@@ -438,6 +473,10 @@ module ActiveRecord
         super(table_name, options.reverse_merge(:options => "ENGINE=InnoDB"))
       end
 
+      # Renames a table.
+      #
+      # Example:
+      #   rename_table('octopuses', 'octopi')
       def rename_table(table_name, new_name)
         execute "RENAME TABLE #{quote_table_name(table_name)} TO #{quote_table_name(new_name)}"
       end
@@ -517,14 +556,16 @@ module ActiveRecord
         end
       end
 
+      # SHOW VARIABLES LIKE 'name'.
       def show_variable(name)
         variables = select_all("SHOW VARIABLES LIKE '#{name}'")
         variables.first['Value'] unless variables.empty?
       end
 
+      # Returns a table's primary key and belonging sequence.
       def pk_and_sequence_for(table)
         keys = []
-        result = execute("describe #{quote_table_name(table)}")
+        result = execute("DESCRIBE #{quote_table_name(table)}", 'SCHEMA')
         result.each(:symbolize_keys => true, :as => :hash) do |row|
           keys << row[:Field] if row[:Key] == "PRI"
         end