Comparing Rows in a VB.NET DataGridView

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Comparing Rows in a VB.NET DataGridView

techsupt

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September 1, 2008 at 7:21 am

#211926

Hi,
I have batches of 3 rows, what is the easiest way to compare these 3 rows to determine which row has the highest value in a specific column within these 3 rows please?
Thanks,
Best Regards,
BMM

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Ron McCullough SSC Guru Points: 63877 More actions · Answer 1

Rather obscure question ... need more information in order to assist you

Suggest you read the article in my signature block and supply requested information so that some one may help.

If everything seems to be going well, you have obviously overlooked something.

Ron

Please help us, help you -before posting a question please read[/url]
Before posting a performance problem please read[/url]

techsupt SSC-Addicted Points: 474 More actions · Answer 2

My project involves the input and calculation of horse racing related data.

I have a button that loads a table's contents into a datagridview component - this can be

all the data, information for a specific date or information from a specific race.

One of the databases stores the results of a calculation which produces 3 horses from any

given race - this database will contain 3 horses from any race stored in the main database.

Within each set of 3 horses, I am looking for a method of comparing specific columns of

data to find the highest value within a specific column. The above screen capture should

provide a better understanding of what I am trying to achieve.

If further information is required to assist me in finding a solution to this problem, then

please let me know.

Thanks

Jonathan Kehayias One Orange Chip Points: 26778 More actions · Answer 3

Its not a SQL Solution, but you can do it in your .NET application by enumerating the DataGridView.Rows collection and for each DataGridViewRow look at the column you want by name.

for (int i=0; i<dgv_Actions.Rows.Count; i++)

{

DataGridViewRow dgvr = dgv_Actions.Rows;

DataGridViewTextBoxCell namecell = (DataGridViewTextBoxCell)dgvr.Cells["dgvActions_Name"];

DataGridViewCheckBoxCell chkcell = (DataGridViewCheckBoxCell)dgvr.Cells["dgvActions_Selected"];

if (sessionevent.ActionString.Contains(namecell.Value.ToString()))

_ActionList.Selected = true;

}

The above is an example from a opensource app that I am working on that is on codeplex. There is a DataGridView name dgv_Actions that has a DataGridViewTextBoxCell named dgvActions_Name and a DataGridViewCheckBoxCell named dgvActions_Selected. I use it to iterate over check the checked items and set a flag on an object based on whether the box it checked, but the code sample should be enough for you to see how to enumerate the collection, and access the specific column by name.

To do it in TSQL, if you are on SQL 2005, you could use a series of CTE's to mark the row in each grouping with a bit 1 = max row, 0 = not max row, or you could use a table variable/temp table as a intermediate storage point, and update a bit column for the max row, and then select the data from the table variable/temp table for return to the application.

Enumerating the collection in the .NET app may or may not be faster, but probably should be faster, depending on the complexity of the logic.