SQL语句查询某字段最大的数??

Question

  string strConnection = "Provider=Microsoft.Jet.OLEDB.4.0;Jet OLEDB:DataBase Password=Local@July,2005;" + "Data Source=" + Application.StartupPath + "/" + "localvod.mdb";
            using (OleDbConnection myConnection = new OleDbConnection(strConnection))
            {
                myConnection.Open();
                OleDbCommand cmd = new OleDbCommand("select top 1 [SONGNO] from [songs] order by [SONGNO] DESC", myConnection);
                OleDbDataReader dr = cmd.ExecuteReader();
                string numbe = dr["SONGNO"].ToString();
                int number=int.Parse(numbe)+1;
                return number;
            } 
dr["SONGNO"].ToString();抱错"不存在此行/列数据"
SONGNO字段数据一定是有的.不知道为什么抱错

Answer 1

select max(SONGNO) from songs

Answer 2

OleDbCommand cmd = new OleDbCommand("select max(SONGNO) from [songs]", myConnection); 

Answer 3

string strConnection = "Provider=Microsoft.Jet.OLEDB.4.0;Jet OLEDB:DataBase Password=Local@July,2005;" + "Data Source=" + Application.StartupPath + "/" + "localvod.mdb"; 
            using (OleDbConnection myConnection = new OleDbConnection(strConnection)) 
            { 
                myConnection.Open(); 
                OleDbCommand cmd = new OleDbCommand("select top 1 [SONGNO] as sg from [songs] order by [SONGNO] DESC", myConnection); 
                OleDbDataReader dr = cmd.ExecuteReader(); 
                string numbe = dr["SONGNO"].ToString(); 
                int number=int.Parse(numbe)+1; 
                return number; 
            } 
dr["sg"].ToString();抱错"不存在此行/列数据" 
SONGNO字段数据一定是有的.不知道为什么抱错 
为什么要加[]？？？

Answer 4

  using (OleDbConnection myConnection = new OleDbConnection(strConnection))
            {
                myConnection.Open();
                OleDbCommand cmd = new OleDbCommand("select top 1 [SONGNO] from [songs] order by [SONGNO] DESC", myConnection);
                OleDbDataReader dr = cmd.ExecuteReader();
                string numbe=string.Empty;
                int number=0;
                where(dr.Read())
               {
                 numbe = dr["SONGNO"].ToString();
                 number=int.Parse(numbe)+1;
               }
                return number;
                
            } 

Answer 5

还有少了 dr.Read()；这句话

Answer 6

你的sql语句怎么这么写呀
效率太低了
直接用max函数就可以了
select max(songno) from songs