Code
    public float GetGroupScore(int iPID, int iEIID, string evaluateTeam)
        {
            SqlParameter[] paras = {
                                       new SqlParameter("@iPID",iPID),
                                       new SqlParameter("@iEIID",iEIID),
                                       new SqlParameter("@evaluateTeam",evaluateTeam),
                                       new SqlParameter("@groupActualScore",SqlDbType.Float)
                                   };
            paras[3].Direction = ParameterDirection.ReturnValue;
            SqlHelper.RunProcedure("Pr_PE_GetGroupScore", paras);
            return float.Parse((paras[3].Value.ToString()));
        }

Code
create Proc Pr_PE_GetGroupScore
(
    @iPID int,
    @iEIID int,
    @EvaluateTeam varchar(20)
)
as
declare @groupGrade int
declare @subItemNum int
declare @subItemNumWithSameTeam int
declare @groupActualScore float
declare @score float
select @score=convert(float,sum(iMark))/(case count(*) when 0 then 1 else 9*count(*) end)
from PE_EvaluateRecord r,PE_EvaluateItem i
where r.iEIID=i.iEIID
    and i.iParentID=@iEIID
    and i.EvaluateTeam=@EvaluateTeam
    and r.iPID=@iPID
select @groupGrade=iScore from PE_EvaluateItem
where iEIID=@iEIID
select @subItemNum=count(*) from PE_EvaluateItem
where iParentID=@iEIID
select @subItemNumWithSameTeam=count(*) from PE_EvaluateItem
where iParentID=@iEIID
    and evaluateTeam=@evaluateTeam
set @groupActualScore=round(@groupGrade*convert(float,@subItemNumWithSameTeam)/@subItemNum*@score,2)
return @groupActualScore