Create string using array

void Runcommand(string tableName,Dictionary<string,object>updatevalues, string wherecaluse)
{
  SqlCommand cmd=new SqlCommand(conn);
  cmd.CommandText="update "+tableName +" Set ";
  bool isAdded=false;
  foreach(string key in updatevalues.keys)
  {
    if(isAdded)
    {
      cmd.CommandText+=", ";
    }
    isAdded=true;
    cmd.CommandText+=string.Format("{0}=@{0}",
    cmd.Parameters.Add(new SqlParameter(key,updatevalues[key]);
  }
  cmd.CommandText+=" where "+whereclause;
  cmd.ExcuteNonQuery();
  
}