if not exists(select 1 from syscolumns where id = object_id('EST_NF_ENT_NFE_CANCEL') and name = 'DT_CAD')
begin 
ALTER TABLE dbo.EST_NF_ENT_NFE_CANCEL ADD
	DT_CAD datetime NULL
ALTER TABLE dbo.EST_NF_ENT_NFE_CANCEL ADD CONSTRAINT
	DF_EST_NF_ENT_NFE_CANCEL_DT_CAD DEFAULT GETDATE() FOR DT_CAD
end