How Create a new Column in a Datable and assign value to the newly created column row

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i have generated a datatable from database like this

source destination vehicle Rate
---------------------------------------------------
a b XXX 500
a c xxx 400

After add a column (New_Rate) in the datatable and assign value.

source destination vehicle Rate New_Rate
--------------------------------------------------------------------------------
a b XXX 500 1000
a c xxx 400 800

Here is my code snippet:

SqlDataAdapter adp2 = new SqlDataAdapter("select source, destination, vehicle, rate from pickupdroptariff order by source", conn);
        DataTable dt2 = new DataTable();
        adp2.Fill(dt2);
        dt2.Columns.Add("Rate_New");
        int veh_rate=0;
        if (dt2.Rows.Count > 0)
        {
            for (int j = 0; j < dt2.Rows.Count; j++)
            {
                if(dt2.Rows[j][2].ToString()=="Small Car")
                {
                    veh_rate = Convert.ToInt32(dt2.Rows[j][3].ToString());
                    veh_rate = veh_rate + small;
                    //DataRow row = null;
                    //row[4] = veh_rate.ToString();
                    //dt2.Rows.Add(row);

                    dt2.Rows.Add("small",veh_rate.ToString());
                }
                if(dt2.Rows[j][2].ToString()=="Regular Car")
                {
                    veh_rate = Convert.ToInt32(dt2.Rows[j][3].ToString());
                    veh_rate = veh_rate + regular;
                    dt2.Rows.Add("Regular", veh_rate.ToString());
                }
                if(dt2.Rows[j][2].ToString()=="Luxury Car")
                {
                    veh_rate = Convert.ToInt32(dt2.Rows[j][3].ToString());
                    veh_rate = veh_rate + luxury;
                    dt2.Rows.Add("Luxury", veh_rate.ToString());
                }
            }
        }
        GridView1.DataSource = dt2;
        GridView1.DataBind();

Where:
dt2 is the datatable,
veh_rate stores vehicle rate

But new records are added below of the previous records.

Please help me, thank you very much.

Posted 28-May-12 2:26am

sahabiswarup

Updated 28-May-12 2:40am

Maciej Los

v4

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Comments

Zoltán Zörgő 28-May-12 10:24am

Do you really want to alter the table definition from code? Why? You can have a filed unused (not visible) in some queries, and used in others.

db7uk 28-May-12 17:50pm

you are really better off doing this in SQL code using case statement. Much easier to bind to grid.

sahabiswarup 28-May-12 23:43pm

i am creating a datatable in the cs page so why do i use sql rather using datatable add row/column.

2 solutions

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Rockstar_ · Answer 1 · 2012-05-28T18:19:00

Hi friend,

This below code may help you...

DataTable dt4 = new DataTable();

C#

dt4.Columns.Add("Eid");
       dt4.Columns.Add("Emp_Name");
       dt4.Columns.Add("uname");
       dt4.Columns.Add("Pwd");

foreach (GridViewRow row in Gv.Rows)
{
dr3 = dt4.NewRow();
Label Eid = (Label)row.FindControl("lblEid");
TextBox Ename = (TextBox)row.FindControl("txtEmpname");
TextBox Uname = (TextBox)row.FindControl("txtUname");
TextBox pwd = (TextBox)row.FindControl("txtPwd");
dr3[0] = Eid.Text;
dr3[1] = Ename.Text;
dr3[2] = Uname.Text;
dr3[3] = pwd.Text;
dt4.Rows.Add(dr3);

}
dr3 = dt4.NewRow();
dt4.Rows.Add(dr3);
dt.Clear();
Session.Remove("dt");
dt = dt4.Copy();
Session["dt"] = dt4;
Gv.DataSource = dt4;
Gv.DataBind();

John Orendt · Answer 2 · 2012-05-28T12:05:00

Solution 1

ALTER the original table to add the new column via sql,

SQL

'add column
ALTER TABLE [dbo].[pickupdroptariff] 
add  [Rate_New] [int]

then use UPDATE to fill in the new column for each row.

Posted 28-May-12 12:05pm

John Orendt

Updated 28-May-12 13:18pm

v2