I have difficult when I make sum of a column in datagrid also in datatable

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i have difficult when i make sum of a column in datagrid also in datatable
i have 4 column in datatable when i make a sum in column Qte it goes normal (integer type)
for column "PU"(double type) it goes with error

please help

What I have tried:

Dim sum As Double

       sum = dt.Compute("SUM(PU)", "")

       MsgBox(sum)

Posted 24-Apr-19 22:23pm

Member 14207792

Updated 24-Apr-19 23:26pm

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Member 14207792 25-Apr-19 4:43am

the erro when i execute is
"Utilisation non valide de la fonction d'agrégation Sum() et du type : String.'"

 Dim sum As Object

        sum = dt.Compute("Sum(PU)", "")

        MsgBox(sum.ToString)

Richard MacCutchan 25-Apr-19 5:03am

The error message suggests that "PU" is not a numeric column.

Member 14207792 25-Apr-19 5:18am

what should i do

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OriginalGriff · Answer 1 · 2019-04-24T23:21:00

Solution 1

Start by going back to your data source and looking at the raw data you have stored: teh error message clearly says "You can't use an aggregation function on a string".
This means that whatever data PU holds, it's stored as a string, not as a number - and you need to convert it to a number in order to SUM the values.

I'd strongly recommend that you start with the original data, and if that is a database change it: always store values in the appropriate data type columns: strings are only for string based data such as names, addresses, mobile phones, email, ... Dates should be in DateTime, numbers should be in int, float, double, or decimal.
All strings may seem like the easy route, but it causes you a lot more headaches later ... particularly when someone enters invalid numbers or dates because when you try to use them it's too late to fix a input problem.

Posted 24-Apr-19 23:21pm

OriginalGriff

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Member 14207792 25-Apr-19 6:05am

thanks for help

i get this column where i have error is from textfile and textfile converted from excel and excel from (pdf facture manually entered)this is the source
now i should have sum of this column("PU")
dt.Columns.Add("PU")
this is how i add the column PU without a parametre gettype

OriginalGriff 25-Apr-19 6:14am

So when you read your text file, you convert the columns into the appropriate data types instead of just treating them as a string.

Member 14207792 25-Apr-19 9:41am

yes exactly i converted it in many way to a double and when execute the sum no result

OriginalGriff 25-Apr-19 9:54am

And when you converted it, what did you do with the converted values?

Member 14207792 25-Apr-19 9:58am

fisrt step i convert the column type directly to double and gives me an error says that data is can't be double like

Nrow("PU") = CDbl(TxtVals(3))

error is
{ 'La conversion de la chaîne "8.24" en type 'Double' n'est pas valide.'}

OriginalGriff 25-Apr-19 10:05am

Use the debugger and find out why: 8.24 is a valid Double value, so the actual string you are converting must include characters that aren't numeric or decimal point, or the Culture settings of the PC are set to use a characters other than '.' as a decimal separator.

Member 14207792 25-Apr-19 12:10pm

yes this is the problem thank god now i can figure it out
i change the "." with "," and it work and goes to the next value
now i need to set that "," to be "."
any idea how i can do it please

Richard MacCutchan · Answer 2 · 2019-04-24T23:27:00

Solution 2

You must declare the column's datatype so that the SUM function understands the data. Add the following line to your dataTable definition:

C#

DataColumn dtc = dt.Columns["PU"];
dtc.DataType = System.Type.GetType("System.Double");

Posted 24-Apr-19 23:27pm

Richard MacCutchan

Comments

Member 14207792 25-Apr-19 6:07am

when i try to add datatype to the column i have error

  dt.Columns.Add("PU", GetType(Double))

{'Le format de la chaîne d'entrée est incorrect.Impossible de stocker <71.84> dans la colonne PU. Type attendu est Double.'}

Richard MacCutchan 25-Apr-19 6:27am

There is something wrong with your data, but we cannot see it.

Richard Deeming 25-Apr-19 9:45am

At a guess, is your computer set to a culture which uses "," as the decimal separator, but the data you're trying to import is using "." instead?

Member 14207792 25-Apr-19 9:48am

the data i import use "."
and how to set the computer to use "," or "."

Richard Deeming 25-Apr-19 9:56am

For .NET 4.5 or higher:
CultureInfo.DefaultThreadCurrentCulture Property (System.Globalization) | Microsoft Docs[^]

This will set your application to the "invariant" culture, which is effectively US English:

CultureInfo culture = CultureInfo.InvariantCulture;

CultureInfo.DefaultThreadCurrentCulture = culture;
CultureInfo.DefaultThreadCurrentUICulture = culture;

Thread.CurrentThread.CurrentCulture = culture;
Thread.CurrentThread.CurrentUICulture = culture;

Member 14207792 26-Apr-19 11:13am

i still haven't resolve it always it demand to be "," not "."

OriginalGriff 25-Apr-19 12:42pm

Best way is not to use the casting operations, but use TryParse instead - which lets you specify the Culture that the number will be expected to be in:
https://docs.microsoft.com/en-us/dotnet/api/system.double.tryparse?view=netframework-4.8#System_Double_TryParse_System_String_System_Globalization_NumberStyles_System_IFormatProvider_System_Double__

Richard MacCutchan 25-Apr-19 7:14am

You are adding the column data as text strings. You must convert it to double values first.

Member 14207792 25-Apr-19 9:40am

i tested everything and no soltuion
i tried to delete the number after the point and it work
so what i can ndo in this case

Richard MacCutchan 25-Apr-19 10:05am

See the suggestion from Richard Deeming above.

Member 14207792 25-Apr-19 7:22am

only string that work with column "PU"
i tried Int32 and double always same error
{'Le format de la chaîne d'entrée est incorrect.Impossible de stocker <71.84> dans la colonne PU. Type attendu est Double.'
}

Richard MacCutchan 25-Apr-19 8:38am

You need to learn the difference between strings and numbers.

Member 14207792 25-Apr-19 9:22am

maybe

Richard MacCutchan 25-Apr-19 10:03am

I don't think there is any maybe about it. If you do not understand how to import a textual representation of a number and convert it to a proper computer based numerical value, then you are going to face many problems.

Member 14207792 25-Apr-19 7:24am

its like the point that in textfile made this difficult for me