Question

I am trying to do a simple financial table that compares the actual to the budgeted figures and show the variance.

**Actual**
ID          Revenue
1           100
2           120

**Budget**
ID          Revenue
1           120
2           100

Once compared it will give me this table:

**Variance**
ID          Revenue
1           -20
2           +20

This is how I got my two tables setup right now:

        // Make the Actual table
        DataTable allActual = new DataTable("actualTable");
        DataRow rowActual;

        // Create columns and add to the DataTable.
        allActual.Columns.Add("Title", typeof(string));
        allActual.Columns.Add("Revenue", typeof(string));

        // Add rows to the Actual grid
        foreach (SPListItem item in actualItems)
        {
            rowActual = allActual.Rows.Add();
            rowActual["Title"] = item["Title"].ToString();
            rowActual["Revenue"] = item["Revenue"].ToString();
        }


        // Make the Budget table
        DataTable allBudget = new DataTable("budgetTable");
        DataRow rowBudget;

        // Create columns and add to the DataTable.
        allBudget.Columns.Add("Title", typeof(string));
        allBudget.Columns.Add("Revenue", typeof(string));

        // Add rows to the Actual grid
        foreach (SPListItem item in budgetItems)
        {
            rowBudget = allBudget.Rows.Add();
            rowBudget["Title"] = item["Title"].ToString();
            rowBudget["Revenue"] = item["Revenue"].ToString();
        }

I would appreciate any help in pointing me to the right answer. Thanks.

Answer 1

You could use LINQ-To-DataSet to get the difference:

Edit: Here is the C# version of the Dictionary-approach(use a simple ToList to get a list of this anonymous type):

var diff = (from  aRow in tblActual.AsEnumerable()
            join bRow in tblBudget.AsEnumerable()
            on aRow["ID"] equals bRow["ID"]
            let aRev = (int)aRow["Revenue"]
            let bRev = (int)bRow["Revenue"]
            where aRev != bRev
            select new 
            {
                ID = (int)aRow["ID"],
                Diff = aRev - bRev
            }).ToDictionary(r => r.ID, r=> r.Diff );

VB.NET:

Dim diff = (From aRow In tblActual
            Join bRow In tblBudget _
            On aRow("ID") Equals bRow("ID")
            Let aRev = DirectCast(aRow("Revenue"), Int32)
            Let bRev = DirectCast(bRow("Revenue"), Int32)
            Where aRev <> bRev
            Select New With {.ID = DirectCast(aRow("ID"), Int32),
                            .Diff = aRev - bRev}).ToList


For Each d In diff
    Dim id = d.ID
    Dim revDifference = d.Diff
Next

Or create a Dictioary(Of Int32, Int32) if you want to lookup a difference for a given ID:

Dim diff = (From aRow In tblActual
            Join bRow In tblBudget _
            On aRow("ID") Equals bRow("ID")
            Let aRev = DirectCast(aRow("Revenue"), Int32)
            Let bRev = DirectCast(bRow("Revenue"), Int32)
            Where aRev <> bRev
            Select New With {.ID = DirectCast(aRow("ID"), Int32),
                            .Diff = aRev - bRev}).
                            ToDictionary(Function(r) (r.ID), 
                                         Function(r) (r.Diff))

' returns diff for a given ID '
Dim diffForID2 = diff(2)
' iterate all dictionary entries '
For Each d In diff
    Dim id = d.Key
    Dim revDifference = d.Value
Next