IF NOT EXISTS (SELECT * FROM SYS.COLUMNS  WHERE NAME = 'FLAG_OBS_DIFAL'    AND  OBJECT_ID = OBJECT_ID('GLB_OBS_NF_PAD'))
begin
ALTER TABLE dbo.GLB_OBS_NF_PAD ADD
	FLAG_OBS_DIFAL int NOT NULL CONSTRAINT DF_GLB_OBS_NF_PAD_FLAG_OBS_DIFAL DEFAULT 0
end