inquiry Data from data table to datagridview with filters - vb.net

Question

i have datatable "dataitems" contain 98000 Rows And Datagridview have 11000 row
want to add the quantity form the datatable to the datagridview every item in it's row in the datagrid view
i am using this code but its take too too too much time to run and sometimes stop responding i need ideas to make it faster to run
Dim dt As New DataTable = najrndataset.dataitems
Dim Total As Integer
for x = 0 to datagridview1.rows.count -1
Dim b = datagridview1.rows(x).cells(1)
Dim c = 3
Total = (From r As DataRow In dt.AsEnumerable
Where r.Field(Of String)("Item_Number") = b And r.Field(Of Integer)("SOP_Type") = c
Select r.Field(Of Integer)("Quantity")).Sum
datagridview1.Rows(x).Cells(0).Value = Total
next

Answer 1

Hopefully you appreciate that if you have 11000 rows in a datagridview (terrible idea, by the way) and 98000 rows in a datatable, and you're running a loop that searches the table for each of the 11K items, and it does this by starting at number 1, and searching 98000 items for it, then going to 2 and searching 98000 items for it til you reach 11000 and searching 98000 items for it... At the end of the operation you're going to have performed 11000 x 98000 operations.. i.e. you're going to have performed 1.078 BILLION operations. This is why "its take too too too much time to run and sometimes stop responding" :)
You can speed this up by using a dictionary to track the sums, and it'll probably be fastest to index the 98000 items then set the dictionary from them:
Dim d as New Dictionary(Of String, Integer)
For Each di In najrndataset.dataitems.Where(Function(r) r.SOP_Type = 3)
If Not d.ContainsKey(di.Item_Number) Then
d(di.Item_Number) = di.Quantity
Else
d(di.Item_Number) += di.Quantity
End If
Next di
Then edit your grid (ugh; this isn't how datagridview are supposed to be used)
datagridview1.SuspendDrawing()
For x = 0 to datagridview1.rows.count - 1
Dim b = datagridview1.rows(x).cells(1)
Dim s As Integer
If d.TryGetValue(b, s) Then
datagridview1.rows(x).cells(0) = s
End If
Next x
datagridview1.ResumeDrawing()
You could also have a logic of "loop over the datagrid, putting 11000 items in the dictionary, loop over the datatable accumulating sums into the dictionary if the keys are present in the dictionary, loop over the datagriview putting the sums into the datagridview".

Answer 2

Not an answer, but too long for a traditional comment. I'm working to provide an answer separately.
I can't tell you how many times I've seen code like this:
Dim someVariable As New SomeObject
someVariable = someMethodToReturnSomeObject()
This pattern is bad code!
The New operator in the first line tells the compiler you want to allocate memory and run the constructor for your type. However, the next line assigns a new object... it throws away and forgets the memory and constructor work from the previous line. That's wasteful.
Instead, you want this:
Dim someVariable As SomeObject = someMethodToReturnSomeObject()
Worse, this speaks to a profound lack of understanding of the difference between a reference and an object, and what the computer is doing with your code in memory. This is a core principle of how many programming environments work. Code like the first example gives me big doubts of the capability of the programmer who writes it.