declare @Descricao as varchar(200)

select top 1 lt.txtDescricao
from gpv_promocoes p
inner join GPV_Log l
on p.codPromocao = l.cod_objeto
inner join GPV_Log_Tipo lt
on lt.cod_tipolog = l.cod_tipolog
where p.codPromocao = @codPromocao and lt.txtDescricao = @Descricao

DECLARE @var nvarchar(200)
select @var = top 1 field1 from table1

return @Var.

create function fn1
@Param nvarchar(100)
returns nvarchar(200)
as
BEGIN
Return (Select top 1 field1 from table1 where Field2 = @Param)
END