Find closest Date to specific Date - excel

Question

I have two Tables.
Table1 goes from A1:F10 and shows the machine assignment.
Table2 goes from G1:K10 and shows the storage for the machines.
With a button I want to simulate which storage should be used for which machine.
In column C stands the date when the machine has to be built. In Column I stands the date when the storage is ready to use.
For example: The first machine has to start on 08/15/2018. How can I check which date in Column I is the closest to 08/15/2018?
This is my code so far:
Private Sub CommandButton1_Click()
Dim lastrow as Long
lastrow = ActiveSheet.Cells(Rows.Count, "A").End(xlUp).Row
for a = 1 to lastrow
If Cells(a, 1) = "Machine Name" And _ ' Find the specific machine
Cells(a, 4) = "" Then ' In this cell the serial number of the storage should be added
' Now check if Storage for this machine is ready to use.
For b = 1 to lastrow
If Cells(b, 8) = "123" And _ ' Serial Number of the Storage
Cells(b, 10) = "" Then ' In this Cell serial number of the machine should be added
' Here it should check which Date in Column I is the closest to the date in Column C
Cells(a, 4).Value = Cells(b, 8)
Cells(b, 10).Value = Cells(a, 2)
End If
Next b
End If
Next a
End Sub
I tried to change the code from Find closest date to current date in VBA.
In the picture you can see an example how the table looks:

Answer 1

you didn't specify where you want the closest date before start so i just added the date as a comment to the start date in column C.
Sub FindClosestBeforeDate()
Dim ws As Worksheet
Dim lLastReadyUsed As Long
Dim lLastStartUsed As Long
Dim dt As String
Dim temp As Variant
Set ws = Application.ThisWorkbook.ActiveSheet
lLastStartUsed = ws.Cells(Rows.Count, "C").End(xlUp).Row
lLastReadyUsed = ws.Cells(Rows.Count, "I").End(xlUp).Row
'Delete previous comments
For l = 2 To lLastStartUsed
If Not Range("c" & l).Comment Is Nothing Then
ws.Range("C" & l).Comment.Delete
End If
Next l
'add comments with closeste date before startdate
For l = 2 To lLastStartUsed
For i = 2 To lLastReadyUsed
If DateDiff("D", ws.Range("C" & l).value, ws.Range("I" & i).value) < 0 Then
If IsEmpty(temp) Then
temp = DateDiff("D", ws.Range("C" & 3).value, ws.Range("I" & i).value)
dt = ws.Range("I" & i).value
ElseIf temp < DateDiff("D", ws.Range("C" & 3).value, ws.Range("I" & i).value) Then
temp = DateDiff("D", ws.Range("C" & 3).value, ws.Range("I" & i).value)
dt = ws.Range("I" & i).value
End If
End If
Next i
temp = Empty
ws.Range("C" & l).AddComment dt
Next l
End Sub
Hope this helps you out

Answer 2

With your example, im assuming you want
Start = 15.06.2018, Ende = 14.03.2018
Start = 25.08.2018, Ende = 26.07.2018
Add this Function and call it like YourCell.Value = getClosestDateBefore(StartCell.Value, Range("I2:I9"))
Function getClosestDateBefore(d As Date, RefDateRange As Range) As Date
Dim i As Long, ref_date As Date, diff As Double, best_diff As Double
best_diff = -10000000
With RefDateRange
For i = 1 To .Cells.Count
ref_date = .Cells(i).Value2
diff = ref_date - d
If diff < 0 And diff > best_diff Then
best_diff = diff
getClosestDateBefore = ref_date
End If
Next i
End With
End Function