[Solved] how to add a new column to sum columns in datagridview

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I have tried as below given code. new column adding without any issue and not showing any errors also. but the problem is not showing any values, even manual typing also not holding. it was clearing itself once we come out from cell. Please help me. Thanks in advance.

What I have tried:

in Form_Shown(...) event:

VB

Dim tmpCol As New DataGridViewTextBoxColumn

tmpCol.Name = "Bal"
tmpCol.HeaderText = "Balance"
tmpCol.CellTemplate = New DataGridViewTextBoxCell

Me.DGV_Details.Columns.Insert(8, tmpCol)

For Each ro As DataGridViewRow In Me.DGV_Details.Rows
	Dim inc, exp As Double
	inc = ro.Cells("Income").Value
	exp = ro.Cells("Expence").Value
	ro.Cells("Bal").Value = inc - exp
Next

Posted 6-Apr-24 6:24am

Member 12254178

Updated 20-Apr-24 5:12am

v3

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Dave Kreskowiak 6-Apr-24 13:13pm

If your DGV is bound to a datasource, which it should always be, you have to add the column to the datasource, do that calculations there, and you can add a new column to the DGV and bind it to the new column in the datasource.

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OriginalGriff · Answer 1 · 2024-04-06T19:24:00

Start by using the debugger to find out exactly what values you are getting.: my guess would be that there are no rows of data yet (i.e. you haven't loaded the data into the DGV at that point) - but we have no idea how you set up your DGV and your data, so we can't tell.

It's probably a bad idea to do it that way anyway - you should use the underlying data source instead of modifying the DGV rows themselves (i.e. the DataTable or Collection that you load the DGV from, preferably by binding it to the DGV) as it means that adding filtering / sorting to the data at a later date becomes considerably easier.

If I try it here by adding a column to a databound DGV and then processing each row after the DataSource has been set, it works fine (except I obviously have to cope with the blank row at the end).

Maciej Los · Answer 2 · 2024-04-08T09:46:00

I'd suggest to read this: DataColumn.Expression Property (System.Data) | Microsoft Learn[^]
This is a very easy way to create computed column :)

See:

VB.NET

Dim dt As DataTable = New DataTable()
dt.Columns.Add("id", Type.GetType("System.Int32"))
dt.Columns.Add("price", Type.GetType("System.Decimal"))
dt.Columns.Add("tax", Type.GetType("System.Decimal"))
Dim cc = dt.Columns.Add("priceandtax", Type.GetType("System.Decimal"))
cc.Expression = "price + (price * tax)"

dt.Rows.Add(1, 50.0, 0.08)
dt.Rows.Add(2, 50.0, 0.22)
dt.Rows.Add(8, 20, 0.05)
dt.Rows.Add(9, 20, 0.03)
DataGridView1.DataSource = dt

[Solved] how to add a new column to sum columns in datagridview

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