c# DataView& DataGridView sorting

Question

I have a small problem. I need to sort data in the DataGridView (WinForms application) in descending order. I apply a DataView as DataSource to myGrid:

DataView view = myDataTable.DefaultView;
view.Sort = "id DESC";
myGrid.DataSource = view;

id column is string data type, and is in ##/yy format. First part is incrementing integer, second part (after '/') is last two digits of current year. Unfortunately it has to be in this format.

After sortting it returns in this order:

9/14,8/14,7/14,6/14,5/14,4/14,3/14,2/14,10/14,1/14...

But it should be like this:

10/14,9/14,8/14,7/14,6/14,...

What would be the easiest way to solve this? Thank you.

EDIT: Added some more info...

Oh...now I know why it doesnt sort in right order...because it is a string (it is in ###/yy format). Is there a way to sort it even if it is a string? — user1080533
– user1080533, Commented Feb 25, 2014 at 20:33
Possible duplicate of stackoverflow.com/questions/7572685/… — Dmitry
– Dmitry, Commented Feb 25, 2014 at 20:40
@Dmitry: Although the questions are similar, this is not a duplicate after the clarification was added. This deals with extra steps to split the string and process it. — grovesNL
– grovesNL, Commented Feb 25, 2014 at 22:23

grovesNL · Accepted Answer · 2014-02-25 22:22:11Z

1

You have a few options here. You can clone your table and modify the type and typecast it properly by modifying the values directly, or you can use a helper column, etc. This can be accomplished many ways. I'll give you a simple example that uses a single helper column to process the string into a date then sort in that way.

If you have some integer (I'll use a 16-bit integer as the type) and a two-digit year separated by a /, we can write it instead as follows:

// Setup a sample table to match yours
DataTable myDataTable = new DataTable();
myDataTable.Columns.Add("id", typeof(string));

// Add some values to the table
myDataTable.Rows.Add("7/14");
myDataTable.Rows.Add("4/14");
myDataTable.Rows.Add("8/14");
myDataTable.Rows.Add("3/14");
myDataTable.Rows.Add("6/14");
myDataTable.Rows.Add("10/14");
myDataTable.Rows.Add("5/14");
myDataTable.Rows.Add("2/14");
myDataTable.Rows.Add("9/14");
myDataTable.Rows.Add("1/14");

// Add a helper column with 16-bit format based on the values in id
myDataTable.Columns.Add("helper", typeof(Int16));

// Convert the value in the id column of each row to a string,
// then split this string at the '/' and get the first value.
// Convert this new value to a 16-bit integer,
// then save it in the helper column.
foreach (DataRow row in myDataTable.Rows) row["helper"] =
    Convert.ToInt16(row["id"].ToString().Split('/')[0]);

// Create a view to match yours, sorting by helper column instead of id
DataView view = myDataTable.DefaultView;
view.Sort = "helper DESC";
//myGrid.DataSource = view;

// Write the output from this view
foreach (DataRow row in view.ToTable().Rows) Console.WriteLine(row["id"]);

which produces the output...

If you need to sort by year as well, you can add an additional helper column in the same manner.

edited Feb 25, 2014 at 22:22

answered Feb 25, 2014 at 21:00

grovesNL

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2 Comments

user1080533 Over a year ago

hi, thank you for this answer, unfortunately it is not yyyy/mm. First part (before the '/') is incrementing integer, second part (after '/') is last two digits of the year. It has to be in this format unfortuantely...

user1080533 Over a year ago

I did add a second helper column to sort by year also, as you suggested. This solution works nicely

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