Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
dtProducts = New DataTable("Products")
dtProducts.Columns.Add("ID", GetType(Int32))
dtProducts.Columns.Add("Name", GetType(String))
dtProducts.Columns.Add("Quality", GetType(Double))
dtProducts.Columns.Add("Price", GetType(Double))
dtProducts.Columns.Add("Sum", GetType(Double))

'---- this columns i need to calculate quality * Price= sum

With dtProducts.Columns("ID")

.AutoIncrement = True
.AutoIncrementSeed = 1
End With

dsNorthwind = New DataSet("Northwind")
dsNorthwind.Tables.Add(dtProducts)
dgProducts.DataSource = dsNorthwind
dgProducts.DataMember = "Products"

End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
dsNorthwind.WriteXml(xmlFile)

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If File.Exists(xmlFile) Then
dsNorthwind.ReadXml(xmlFile)

End If

End Sub
End Class

Just put the expression

---

Arjun Paudel

Hi AgronSverkaj,

If you want to calculate the sum of certain column, you can write code like this:

Does this works for you? If you have any questions or concerns, please update the thread and we will have a further discussion.

Best Regards

Yichun Feng

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.

Just put the expression

---

Arjun Paudel

Hi AgronSverkaj,

If you want to calculate the sum of certain column, you can write code like this:

Does this works for you? If you have any questions or concerns, please update the thread and we will have a further discussion.

Best Regards

Yichun Feng

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.

Hi AgronSverkaj,

Try this:
total = total + (CType(dt(i)("sum"), Double))

And if it doesn't work, please give the description of error message. So that we can better idea of you problem.

Best Regards

Yichun Feng

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.

Dim i As Integer

Dim total As Double = 0

For i = 0 To dtProducts.Rows.Count - 1

total = total + (

CType(dt(i)("sum"), Double))

'By dt is error the msg is name dt is not declared this is dhe message of errore

Next

MsgBox(total)