sum column in datatable vb.net 2010

Question

I am trying to get the sum of the column TotalAmount in my DataTable dt but I always get this error:

Object reference not set to an instance of an object.

I am using VB in Visual Studio 2012.

Here's the code:

Dim table As DataTable = CartDataSet.Tables("dt")
Dim result As Integer
result = table.Compute("SUM(TotalAmount)", "")

Screenshot

http://stackoverflow.com/q/4660142/1402846 – Pang Aug 03 '14 at 05:29 — Pang, Aug 03 '14 at 05:29

score 3 · Answer 1 · answered Jul 27 '17 at 17:24

3

Dim result As Object
result = table.Compute("SUM(TotalAmount)", "")

then do result.ToString() you will get your output

answered Jul 27 '17 at 17:24

Amit Patel

147
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score 1 · Answer 2 · answered Aug 03 '14 at 05:30

1

You are trying to de-reference a NULL object reference, which means table is NULL.

That in turn, means CartDataSet does not contain a table named "dt"

answered Aug 03 '14 at 05:30

Mitch Wheat

280,588
41
444
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score 0 · Answer 3 · answered Nov 14 '14 at 05:43

Possible Issues

Table is null
No records in the table

Solutions:

1- Better to check the datatable status before computation like

If Not table Is Nothing AndAlso table.Rows.Count > 0 Then
...
End If

2- Check for DBNULL while computing in case no records

IIf(IsDBNull(table.Compute("SUM(TotalAmount)", "")), "0", table.Compute("SUM(TotalAmount)", ""))

score 0 · Answer 4 · edited Oct 24 '15 at 05:14

0

Dim dt As DataTable = TajDataSet.Tables("MAtab")
Dim sum As Integer = Convert.ToInt32(dt.Compute("SUM(ServiceCharge)", String.Empty))
SCC.Text = sum.ToString

edited Oct 24 '15 at 05:14

Vivek S.

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answered Jul 12 '15 at 05:34

Yocto Karthi

11
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1

Couly you please destribe your code instead oj just typing some code lines – bish Jul 12 '15 at 05:59

score 0 · Answer 5 · answered Aug 13 '15 at 20:03

0

For the ".Compute" function to work, you have to declare your variable "result" as "object" instead of "integer". Then later you can convert the value in "result" to an integer using "Convert.ToInt".

Dim result as object

answered Aug 13 '15 at 20:03

DCraft

1

score 0 · Answer 6 · answered Aug 15 '17 at 15:00

0

You can use linq, like this.

Dim result As Decimal = dt.AsEnumerable().Sum(Function(row) row.Field(Of Decimal)("TotalAmount"))

answered Aug 15 '17 at 15:00

Quethzel Díaz

479
1
9
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score 0 · Answer 7 · answered Sep 03 '20 at 17:20

0

Dim table As DataTable = CartDataSet.Tables("dt")

Dim result As Integer

result = IIf(IsDBNull(dtable.Compute("SUM(TotalAmount)",""),0,dtable.Compute("SUM(TotalAmount)", ""))

answered Sep 03 '20 at 17:20

Andres Sarria

1

sum column in datatable vb.net 2010

7 Answers7