if not exists(select 1 from syscolumns where id = object_id('EST_NF_SAI_SERVICOS') and name = 'VLR_BASE_ISSQN')
begin 
ALTER TABLE dbo.EST_NF_SAI_SERVICOS ADD
	VLR_BASE_ISSQN money NOT NULL CONSTRAINT DF_EST_NF_SAI_SERVICOS_VLR_BASE_ISSQN DEFAULT 0,
	PERC_ISSQN money NOT NULL CONSTRAINT DF_EST_NF_SAI_SERVICOS_PERC_ISSQN DEFAULT 0,
	VLR_DEDUCAO money NOT NULL CONSTRAINT DF_EST_NF_SAI_SERVICOS_VLR_DEDUCAO DEFAULT 0,
	VLR_RETENCAO money NOT NULL CONSTRAINT DF_EST_NF_SAI_SERVICOS_VLR_RETENCAO DEFAULT 0,
	VLR_DESC_INCONDICIONADO money NOT NULL CONSTRAINT DF_EST_NF_SAI_SERVICOS_VLR_DESC_INCONDICIONADO DEFAULT 0,
	VLR_DESC_CONDICIONADO money NOT NULL CONSTRAINT DF_EST_NF_SAI_SERVICOS_VLR_DESC_CONDICIONADO DEFAULT 0,
	VLR_RETENCAO_ISSQN money NOT NULL CONSTRAINT DF_EST_NF_SAI_SERVICOS_VLR_RETENCAO_ISSQN DEFAULT 0,
	VLR_ISSQN money NOT NULL CONSTRAINT DF_EST_NF_SAI_SERVICOS_VLR_ISSQN DEFAULT 0
end