求帮忙，存入数据库的错误。ExecuteNonQuery: CommandText 属性尚未初始化

public void insert(string a, string b, string c, string d, string e, string f)
      {       StringBuilder strSql = new StringBuilder();
       strSql.Append("insert into excel(name,tel,dep,yunyins,chongzhi,time) values (@a,@b,@c,@d,@e,@f)");                        
       SqlParameter[] parameters = { 
          new SqlParameter("@a",SqlDbType.VarChar,50),                                          
          new SqlParameter("@b", SqlDbType.VarChar,50),                                          
          new SqlParameter("@c", SqlDbType.VarChar,50),
          new SqlParameter("@d", SqlDbType.VarChar,50),  
          new SqlParameter("@e", SqlDbType.VarChar,50),  
          new SqlParameter("@f", SqlDbType.DateTime,8),                                         
          };
           
          parameters[0].Value = a;
          parameters[1].Value = b;
          parameters[2].Value = c;
          parameters[3].Value = d;
          parameters[4].Value = e;
          parameters[5].Value = f;         string xsr = string.Empty;  这我加的，如果没有，就报错上下文中不存在名称xsr.
         
         if (fnExecuteNonQuery(xsr.ToString(), parameters))  
          {                 
              MessageBox.Show("导入数据库！", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
          }
}public bool fnExecuteNonQuery(string xsr, SqlParameter[] parameters)
      {
          SqlConnection conn = new SqlConnection("Server=xxx;DataBase=xxx;User=xxx;Password=xxx");//按照你的数据库配置连接           
          conn.Open();          SqlCommand sqlCom = new SqlCommand();
          {
              sqlCom.Connection = conn;
              sqlCom.CommandText = xsr.ToString();
              foreach (SqlParameter sqlP in parameters)
              {
                  sqlCom.Parameters.Add(sqlP);
              }
              try
              {
                  sqlCom.ExecuteNonQuery();
              }
              catch (Exception e1)
              {
                  conn.Close();
                  throw new Exception(e1.Message);                  //  return false;               
              }
          }
          conn.Close();
          return true;
      }数据库C#