how to reduce in multiple try catch - asp.net

Question

hi i am beginner to develop a project, in my project i used try catch with in try catch so how i write the query professionally...
my code is....
try
{
//connection();
con = new SqlConnection(constr);
con.Open();
txtcusname.Text = "";
txtcusnumber.Text = "";
query = "sample_SP";
cmd = new SqlCommand(query, con);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#GetCusID", txtcusid.Text).ToString();
da = new SqlDataAdapter(cmd);
ds = new DataSet();
da.Fill(ds);
GrdCustomerDetails.DataSource = ds;
GrdCustomerDetails.DataBind();
con.Close();
try
{
//connection();
con = new SqlConnection(constr);
con.Open();
ViewState["VSCusID"] = txtcusid.Text;
cmd = new SqlCommand("select contname,mob from CustContacts_TB where cid='" + ViewState["VSCusID"] + " '", con);
dr = cmd.ExecuteReader();
dr.Read();
txtcusname.Text = dr["contname"].ToString();
txtcusnumber.Text=dr["mob"].ToString();
con.Close();
}
catch(Exception ex)
{
}
finally
{
//connection();
con = new SqlConnection(constr);
con.Open();
ViewState["VSCusID"] = txtcusid.Text;
//cmd = new SqlCommand("select compname from CustCreate_TB inner join CustContacts_TB on CustContacts_TB.'" + ViewState["VSCusID"] + "'=CustCreate_TB.'" + ViewState["VSCusID"] + "' ", con);
cmd = new SqlCommand("select compname from CustCreate_TB where cid='" + ViewState["VSCusID"] + " ' ", con);
dr = cmd.ExecuteReader();
dr.Read();
txtcompname.Text = dr["compname"].ToString();
con.Close();
//txtcusname.DataBind();
}
}
catch (Exception ex)
{
}
finally
{
//connection();
con = new SqlConnection(constr);
con.Open();
cmd = new SqlCommand("select compliantID,priorty,status from NewComp1 where customerid='" + ViewState["VSCusID"] + "' and status='open'", con);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
grdpending.DataSource = ds;
grdpending.DataBind();
cmd = new SqlCommand("select compliantID,priorty,status from NewComp1 where customerid='" + ViewState["VSCusID"] + "' and status='closed'", con);
da = new SqlDataAdapter(cmd);
ds = new DataSet();
da.Fill(ds);
grdClosed.DataSource = ds;
grdClosed.DataBind();
con.Close();
}
it possible to reduce code and it correct format.... thank you for helping and its useful to develop my coding skills

Answer 1

You essentially have:
try
{
[block1]
try
{
[block2]
}
catch(Exception ex)
{
}
finally
{
[block3]
}
}
catch (Exception ex)
{
}
finally
{
[block4]
}
}
They all seem to fetch data and populate controls or variables. You haven't specified what you would do in an exception, so you could simply have them all in a single try block, or put them all in individual blocks. I can't see why they have to be nested.
Finally is usually used for 'clean up' operations, like disposing of open connections but you seem to be using your Finally for a new select & populate operation, which is wrong.
so:
try
{
[block1]
[block2]
[block3]
[block4]
}
or if you needed to know when a specific block had failed but each in try/catch
try
{
[block1]
}
...
try
{
[block4]
}

Answer 2

why are you making all this connection =???
you may do it
try {
using (System.Data.SqlClient.SqlConnection cnn = new System.Data.SqlClient.SqlConnection()) {
if (cnn.State == ConnectionState.Closed)
cnn.Open();
using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand()) {
//first task
}
using (System.Data.SqlClient.SqlCommand cmd1 = new System.Data.SqlClient.SqlCommand()) {
//second one
}
using (System.Data.SqlClient.SqlCommand cdm2 = new System.Data.SqlClient.SqlCommand()) {
//third task
}
}
} catch (SqlClient.SqlException sqlex) {
//catch exception sql
//to do
} catch (Exception ex) {
//generic exceptio
//to do some stuff
} finally {
//if need to do later
}