How edit dataset column value in asp.net

Question

Hi i have dataset having one table have 5 columns fill data from database.

When i run application datatable contains more than 50 rows, I would like to update value of datatable after getting data from databse. My requirements are

1. This table have few cells having Null value, I would like to replace null with "-" ?
2. One column is System.datetime datatype, where i would like to remove time. I would only like to have date?

I am using this dataset in crystal report of asp.net using PUSH approach.

Here i am thinking that i apply one loop of rows present in datatable and update cells accordingly. But i am searching any direct update method?

Please help me how can i solve above 2 issue?

Answer 1

One part of your question can be done with sql in the database where u just do an update statement and replace those empty cells with a "-". The other part of your question did not become very clear to me. If you asked how to make sure you can edit rows in a datacolumn using a datagrid you can just read this article and you will be able to make the grid go into editable mode.

Answer 2

Looping through the rows, updating the values as you go is definitely a solution, and a quite easy one:

foreach (DataRow row in table.Rows)
{
    if (row.IsNull("foo")) row["foo"] = "-";
    if (row.IsNull("bar")) row["bar"] = "-";
    row["date"] = ((DateTime)row["date"]).Date;
}

Alternatively, you could create new columns in the table, using expressions to autogenerate content:

table.Columns.Add("foo_dash", typeof(string), "IsNull(foo, '-')");
table.Columns.Add("bar_dash", typeof(string), "IsNull(bar, '-')");

(I don't know the date functions in ADO.NET so you will have to figure the last one out yourself.)

You have tagged your post ASP.NET, so I guess it is reasonable to assume that you are going to bind your DataTable to some multi-record data control (GridView, Repeater, etc). If this is the case, it might be better to do the transformations during databinding instead:

protected void theGrid_OnRowDataBound(object sender, GridViewRowEventArgs e)
{
    var data = e.DataItem as DataRowView;
    if (data != null)
    {
        if (data.Row.IsNull("foo")) e.Row.Cells[0] = "-";
        if (data.Row.IsNull("bar")) e.Row.Cells[0] = "-";
    }
}

While this seems to require a bit more code, it also gives you more flexibility. Example:

if (data.Row.IsNull("importantField")) e.Row.CssClass = "error";

In a GridView, the date can be formatted using a DataFormatString in the column declaration:

<asp:BoundField DataField="data" DataFormatString="{0:d}" />

Similar when databinding a Repeater:

<%# Eval("date", "{0:d}") %>