string connstr = "Data Source=.;Initial Catalog=DB_LMS;Integrated Security=True";
string sqlstr = "select * from tb_BookMess";
SqlDataAdapter ad = new SqlDataAdapter(sqlstr, connstr);

DataSet ds = new DataSet();
ad.Fill(ds, "tb_BookMess");

/////获得表的列名

ds.Tables["tb_BookMess"].Columns[i].ToString() ;

////获得表的某行某列的值
string str= ds.Tables["tb_BookMess"].Rows[0][2].ToString();