IF not EXISTS (SELECT 1 FROM SYS.COLUMNS WHERE NAME ='PERC_FECOP_ST_RET' AND OBJECT_ID=OBJECT_ID('EST_NF_ENT_DANFE_PROVISORIO_ITENS_VALIDACAO_IMPOSTO') )
    BEGIN
	   ALTER TABLE EST_NF_ENT_DANFE_PROVISORIO_ITENS_VALIDACAO_IMPOSTO ADD  PERC_FECOP_ST_RET MONEY NULL
    END