Query+Individual assignment of values to fields

Question

The code is:
string conn_str="Provider=MSDAORA.1;User ID=navuser2;Data Source=orcl;Password=navuser2";

OleDbConnection conn=new OleDbConnection(conn_str);
conn.Open();
OleDbCommand cmd = new OleDbCommand();
cmd.CommandText = "select * from TEST";
cmd.Connection = conn;
OleDbDataAdapter adap=new OleDbDataAdapter(cmd);
DataSet dtset=new DataSet();
adap.Fill(dtset,"test");
DataTable tab1;
tab1=dtset.Tables["test"];
int a=600;
string b="axxxxx";
string ins="Insert into test values (" + a + ",'" + b + "'"  + ")";
DataRow r1;
r1=tab1.NewRow();
r1[0]=a;
r1[1]=b;
tab1.Rows.Add(r1);
adap.InsertCommand=new OleDbCommand(ins,conn);
adap.Update( dtset, "test");
conn.Close();

//---end of code----------
In the above code, don’t u think there is redundancy of code. 1st we are writing SQL to insert data, then we are exclusively specifying individual fields of rows(e.g. r1[0]=a ). Is there anyway to avoid this? 
My question is why we are doing the same thing in 2 ways? suppose there are 15 fields. in that case, along with query, we will have to mention 15 fields also.
How to avoid this?