formula in a datagrid column

Hello,

Is it possible to have one column of a datagrid depend on other columns of the datagrid?
For example,
Suppose column A contains 'x' values,
column B contains 'y' values,

then I want column C to contain 'x / y' (x divided by y) values.

Please help. Thanks.


enggAsked:
Who is Participating?
 
bele04Connect With a Mentor Commented:
I'd suggest you go with what Rejo suggested to lessen the work load on your application.  But if you want to do some extra functionality then you can do something like this:

[ASPX Code]

<asp:TemplateColumn HeaderText="CategoryID">
    <ItemTemplate>
 <asp:Label id=Label1 runat="server" Text='<%# DisplayMethod(Container) %>'>
 </asp:Label>
    </ItemTemplate>
</asp:TemplateColumn>

[CodeBehind]

public string DisplayMethod(object c)
{
    if(DataBinder.Eval(c, "DataItem.A").ToString() != "")
    {
        int a = Integer.Parse(DataBinder.Eval(c, "DataItem.A").ToString());
        int b = Integer.Parse(DataBinder.Eval(c, "DataItem.B").ToString());
        string result = "" + (a*b);
        return result;
    }

    return 0;
}
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RejojohnyCommented:
you could do that in the query itself i.e. when u fetch it from database (i assume the data is coming from a database)... no  need to do that in the datagrid ..

select A, B, A*B as C from table

Rejo
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bele04Commented:
oopps...that should have been:

[CodeBehind]

public string DisplayMethod(object c)
{
    if(DataBinder.Eval(c, "DataItem.A").ToString() != "")
    {
        int a = Integer.Parse(DataBinder.Eval(c, "DataItem.A").ToString());
        int b = Integer.Parse(DataBinder.Eval(c, "DataItem.B").ToString());
        string result = "" + (a*b);
        return result;
    }

    return "0";
}
0
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enggAuthor Commented:
Thanks Rejojohny, bele04.

I can't do that directly in the SQL query. Every column in the datagrid is going to be filled in by a different query or a by a different calculation.  each of those queries/calculations is going to be moderately complex.  

I will get back to you soon after I try out bele04's solution.
Thank you.


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enggAuthor Commented:
Hello Rejojohny, bele04,

Sorry for being late.

I used DataTable to store the data and then filled the datagrid using the datatable. .NET DataTable's  'Compute' method and 'Expression' property are useful if we want any column to be dependent on other columns.  
what do you think?

Thanks.


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RejojohnyConnect With a Mentor Commented:
am not aware of the "expression" property, but "compute" is used to compute a value of a single column (avg, sum etc) within multiple rows (not columns) of a datatable for a condition and not within columns as you require .. correct me if I am wrong ..

Rejo
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bele04Commented:
I too am not aware of the Expression property of the DataTable.  I don't think DataTable even has that property.  Did the code I posted above work for you? If not then you can use another approach.

Since you are using a datatable to bind the datagrid then why not manipulate the data in the datatable before you bind it to the datagrid like:

//dt is your datatable
foreach (DataRow dr in dt.Rows)
{
    dr["ColumnC"] = ((int)dr["ColumnA"] * (int)dr["ColumnB"]).ToString();
}
0
 
enggAuthor Commented:
Yeah, Rejo is right.

DataTable's DataColumn has 'Expression' property which can be used to create computed columns or Bele04's approach would work as well.

I will definitely try out bele04's code. Right now, the Datatable approach has worked for me.
Thank you very much for your help.


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