Trying to Concatenate 2 Columns from the Table Directly VBA - excel

Question

I have been trying to Concatenate two Columns directly from the Table1. But i really do not know how. I have tried and make below code.
But I have been creating first 2 helping Column in in "DI" and "DJ" to make this thing work.
I do not want to use these two helping columns directly wants the concatenate result in "DK2"
All help will be appreciaed.
Dim O As String
Dim P As String
O = "Milestone"
P = "Task"
Sheet1.Range("Table1[" & O & "]").Copy
Sheet2.Range("DI2").PasteSpecial xlPasteValues
Sheet1.Range("Table1[" & P & "]").Copy
Sheet2.Range("DJ2").PasteSpecial xlPasteValues
For i = 2 To Cells(Rows.Count, "DH").End(xlUp).Row
Sheet2.Cells(i, "DK").Value = Sheet2.Cells(i, "DI").Value & "" & Sheet2.Cells(i, "DJ").Value
Next i
Here is the example Picture

Answer 1

Try this.
Range("DK2").Resize(Sheet2.ListObjects("Table1").ListRows.Count) = Application.Evaluate("Table1[Milestone]&Table1[Task]")

Answer 2

EDIT: I've seen #norie's answer and it is simpler and more efficient than mine. I'll keep my answer here for anyone who is curious, but I recommend using his solution.
The trick is to use =INDEX(YOUR_TABLE[YOUR_COLUMN]], YOUR_ROW_STARTING_FROM_1) in order to obtain the cell contents that you needed.
Here you are your code edited:
Original
Dim O As String
Dim P As String
Dim i As Integer
O = "Milestone"
P = "Task"
For i = 1 To Application.Evaluate("ROWS(Table1[" & O & "])")
Sheet2.Cells(i, "DK").Value = Application.Evaluate("INDEX(Table1[" & O & "], " & i & ") & INDEX(Table1[" & P & "], " & i & ")")
Next i
Optimized
Dim O As String
Dim P As String
Dim i As Integer
O = "Milestone"
P = "Task"
' Disable formula recalculation while trying to add our data to increase performance
Application.Calculation = xlManual
' Disable screen updating while trying to add our data to improve performance
Application.ScreenUpdating = False
For i = 1 To Application.Evaluate("ROWS(Table1[" & O & "])")
Sheet2.Cells(i, "DK").Value = Application.Evaluate("INDEX(Table1[" & O & "], " & i & ") & INDEX(Table1[" & P & "], " & i & ")")
Next i
' Enable again formula's automatic evaluation.
Application.Calculation = xlAutomatic
' Enable again screen updating
Application.ScreenUpdating = True
Optimized using only Formulas (this performs better that the others)
Dim O As String
Dim P As String
Dim i As Integer
O = "Milestone"
P = "Task"
' Disable formula recalculation while trying to add our data to increase performance
Application.Calculation = xlManual
' Disable screen updating while trying to add our data to improve performance
Application.ScreenUpdating = False
For i = 1 To Application.Evaluate("ROWS(Table1[" & O & "])")
Sheet2.Cells(i, "DK").FormulaR1C1 = "=INDEX(Table1[" & O & "], " & i & ") & INDEX(Table1[" & P & "], " & i & ")"
Next i
' Enable again formula's automatic evaluation.
Application.Calculation = xlAutomatic
' Enable again screen updating
Application.ScreenUpdating = True
Optimized using Formulas and then converting back to values
Dim O As String
Dim P As String
Dim i As Integer
O = "Milestone"
P = "Task"
' Disable formula recalculation while trying to add our data to increase performance
Application.Calculation = xlManual
' Disable screen updating while trying to add our data to improve performance
Application.ScreenUpdating = False
For i = 1 To Application.Evaluate("ROWS(Table1[" & O & "])")
Sheet2.Cells(i, "DK").FormulaR1C1 = "=INDEX(Table1[" & O & "], " & i & ") & INDEX(Table1[" & P & "], " & i & ")"
Next i
' Enable again formula's automatic evaluation.
Application.Calculation = xlAutomatic
' Enable again screen updating
Application.ScreenUpdating = True
' Convert from formulas to values
Range("DK:DK").Copy
Range("DK:DK").PasteSpecial xlPasteValues

Answer 3

This can be done directly in the worksheet by using the Index function
Reference first cell in the table: =INDEX(Table1,1,1)
Concatenate cell 1 and 2 values: =INDEX(Table1,1,1)&INDEX(Table1,1,2)
It gets slightly more complicated if you want to be able to copy formulae across or down as you need to reference the current cell location
Reference first cell in the table using offsets: =INDEX(Table1,ROW()-X,COLUMN()-Y) where X, Y (minus data location offsets) are the numerical row/column of the cell where you have placed the formula.
i.e. if placing the formula in E2 to reference Table1 cell(1,1) => =INDEX(Table1,ROW()-1,COLUMN()-4)
where Column E=> Offset 4, Row 2 => Offset 1
or: =INDEX(Table1,ROW()-ROW($E$2)+1,COLUMN()-COLUMN($E$2)+1)
You can now autofill the formula down or across

Answer 4

Concatenate List Columns
With your amount of data both solutions may seem equally efficient. I've tested it with a million rows of random numbers from 1 to 1000, and the first solution took about 3.5 seconds, while the second took about 5.5 seconds on my machine. The first solution is just a more elaborate version of norie's answer.
In this solution, you can add more columns (headers) and use a delimiter. While adding more columns the difference in the efficiencies will become more apparent, while when adding more characters to the delimiter, the efficiencies will decrease seemingly equally.
The Code
Option Explicit
Sub concatListColumnsEvaluate()
Dim dTime As Double: dTime = Timer
' Define constants.
Const TableName As String = "Table1"
Const HeadersList As String = "Milestone,Task"
Const dFirst As String = "D2"
Const Delimiter As String = ""
' Determine table rows count.
Dim rCount As Long: rCount = Sheet1.ListObjects(TableName).ListRows.Count
' Create Evaluate Expression String.
Dim Headers() As String: Headers = Split(HeadersList, ",")
Dim tUpper As Long: tUpper = UBound(Headers)
Dim evString As String
Dim t As Long
If Len(Delimiter) = 0 Then
For t = 0 To tUpper
evString = evString & TableName & "[" & Headers(t) & "]" & "&"
Next t
evString = Left(evString, Len(evString) - 1)
Else
For t = 0 To tUpper
evString = evString & TableName & "[" & Headers(t) & "]" & "&""" _
& Delimiter & """&"
Next t
evString = Left(evString, Len(evString) - Len(Delimiter) - 4)
End If
' Write values to Destination Range.
Sheet2.Range(dFirst).Resize(rCount).Value = Application.Evaluate(evString)
Debug.Print Timer - dTime
End Sub
Sub concatListColumnsArrays()
Dim dTime As Double: dTime = Timer
' Define constants.
Const TableName As String = "Table1"
Const HeadersList As String = "Milestone,Task"
Const dFirst As String = "D2"
Const Delimiter As String = ""
' Write values from list columns to arrays of Data Array.
Dim Headers() As String: Headers = Split(HeadersList, ",")
Dim tUpper As Long: tUpper = UBound(Headers)
Dim Data As Variant: ReDim Data(0 To tUpper)
Dim t As Long
For t = 0 To tUpper
' Either...
Data(t) = Sheet1.Range(TableName & "[" & Headers(t) & "]").Value
' ... or:
'Data(t) = Sheet1.ListObjects(TableName) _
.ListColumns(Headers(t)).DataBodyRange.Value
Next t
' Concatenate values of arrays of Data Array in Result Array.
Dim rCount As Long: rCount = UBound(Data(0), 1)
Dim Result As Variant: ReDim Result(1 To rCount, 1 To 1)
Dim r As Long
If Len(Delimiter) = 0 Then
For r = 1 To rCount
For t = 0 To tUpper
Result(r, 1) = Result(r, 1) & Data(t)(r, 1)
Next t
Next r
Else
For r = 1 To rCount
For t = 0 To tUpper
Result(r, 1) = Result(r, 1) & Data(t)(r, 1) & Delimiter
Next t
Result(r, 1) = Left(Result(r, 1), Len(Result(r, 1)) _
- Len(Delimiter))
Next r
End If
' Write values from Result Array to Destination Range.
Sheet2.Range(dFirst).Resize(rCount).Value = Result
Debug.Print Timer - dTime
End Sub