SUM[ALL[DISTINCT] 表达式）

USE [Study]
GO
Create Procedure count
AS
select SUM(Num) as NumTotal
from Counts
GO

        int totalNum = 0;
        string datastr = "server=.;database=Study;user id=sa;password=1234567890";
        SqlConnection con = new SqlConnection(datastr);
        con.Open();

        
        SqlCommand mycmd = new SqlCommand("count", con);
        mycmd.CommandType = CommandType.StoredProcedure;
        SqlDataReader read =mycmd.ExecuteReader();
        if (read.Read())
        {
            totalNum = Convert.ToInt32(read["NumTotal"].ToString());
        }
        read.Close();
        mycmd.Dispose();
        con.Close();
        return totalNum;