how to separate fields while updating from one table to another

i got my solution ..
anyway thanks a lot..

there was a mistake in if condition
now it is working perfectly


protected void Button7_Click1(object sender, EventArgs e)
{

DataTable dt = new DataTable();
string query = "select * from table1";
using (SqlConnection con = new SqlConnection(con_str))
{
using (SqlCommand cmd = new SqlCommand(query))
{
using (SqlDataAdapter da = new SqlDataAdapter())
{
cmd.CommandType = CommandType.Text;
cmd.Connection = con;
da.SelectCommand = cmd;
da.Fill(dt);
}
}
}

try
{

string query2;
// string query3;
using (SqlConnection con = new SqlConnection(con_str))
{
con.Open();

foreach (DataRow row in dt.Rows)
{
string str = row["AdviceNo"].ToString();


//The conditions

if (string.IsNullOrEmpty(str))
{


query2 = "update table2 set t2.alldetails_cheque=t1.chequeno from table1 as t1 and table2 as t2
on t1.id=t2.id and t1.name=t2.name where t1.adviceno is null";
SqlCommand cmd2 = new SqlCommand(query2, con);
cmd2.ExecuteNonQuery();
}
else
{
query2 = "update table2 set t2.alldetails_cheque=t1.adviceno from table1 as t1 and table2 as t2
on t1.id=t2.id and t1.name=t2.name where t1.chequeno is null ";
SqlCommand cmd2 = new SqlCommand(query2, con);
cmd2.ExecuteNonQuery();

}

}

con.Close();
}

}
catch (Exception ex)
{
Response.Write(ex.Message);

}
finally
{

Label2.Text = "updated";
}

how would you do via stored procedure with three parameters ??

can u please tell me about it