group and having clause init

lib/smql_to_ar.rb

@@ -101,6 +101,12 @@ class SmqlToAR
 		end
 	end
 
+	class UnknownHavingMethod < SMQLError
+		def initialize expected, got
+			super :expected => expected, :got => got
+		end
+	end
+
 	class BuilderError < Exception; end
 
 	#############################################################################

lib/smql_to_ar/condition_types.rb

@@ -382,6 +382,63 @@ class SmqlToAR
 				end
 			end
 
+			class GroupBy < Function
+				Name = :group
+				Excepted = [String, Array]
+
+				def initialize model, func, args
+					super model, func, args.collect( &Columnt.method( :new))
+				end
+
+				def build builder, table
+					return  if @args.blank?
+					@args.each do |col|
+						t = Column.new *(table + col.to_a)
+						raise_unless 1 == t.length, RootOnlyFunctionError.new( t)
+						builder.group t
+					end
+				end
+			end
+
+			class Having < Function
+				Name = :having
+				Excepted = [Array]
+
+				def initialize model, func, args
+					args = Hash[ *args.collect do |col, meth|
+							col = Column.new col
+							case meth.to_sym
+							when :max, :min
+							else raise UnknownHavingMethod.new( [:max, :min], meth)
+							end
+							[col, meth]
+						end]
+					super model, func, args
+				end
+
+				def build builder, table
+					return  if @args.blank?
+					@args.each do |col, meth|
+						t = Column.new *(table + col.to_a)
+						raise_unless 1 == t.length, RootOnlyFunctionError.new( t)
+						builder.having meth => t
+					end
+				end
+			end
+
+			class Max < Having
+				Name = :max
+				Expected = [String]
+
+				def initialize model, func, args
+					super model, :having, Hash[ *args.collect {|col| [col, func] } ]
+				end
+			end
+
+			class Min < Max
+				Name = :min
+			end
+
 			class Limit < Function
 				Name = :limit
 				Expected = [Fixnum]

lib/smql_to_ar/query_builder.rb

@@ -43,6 +43,7 @@ class SmqlToAR
 			@table_alias[ @base_table] = @base_table.first
 			t = quote_table_name @table_alias[ @base_table]
 			@_select, @_joins, @_joined, @_includes, @_order = ["DISTINCT #{t}.*"], "", [@base_table], [], []
+			@_group, @_having = {}, {}
 			@table_model = {@base_table => @model}
 		end
 
@@ -66,6 +67,14 @@ class SmqlToAR
 			self
 		end
 
+		def group col
+			@_group.push col
+		end
+
+		def having h
+			@_having.update h
+		end
+
 		def quote_column_name name
 			@quoter.quote_column_name( name).gsub /"\."/, ','
 		end