How to output date value from a text - sql

Question

So I have obfuscated date information in my column. e.g. Jan preplan-2017, Feb-afterplan-2017-low, etc.
Two things are always consistent: Months always come in the beginning with 3 letters. And year comes in 4 digits (may in anywhere.)
I basically need them in the standard date format( e.g. 1/1/2017, 1/2/2017, etc.)

Answer 1

First convert your string to a date value:
s = "Jan preplan-2017"
TrueDate = DateValue("1 " & Left(s, 3) & " " & Right(s, 4))
Then - for display - format as required:
ShowDate = Format(TrueDate, "d.m.yyyy")
Or in one go:
ShowDate = Format(DateValue("1 " & Left(s, 3) & " " & Right(s, 4)), "d.m.yyyy")
Edit: Use Split to create an array of the elements, loop these and pick the one that is an integer:
Year = Split("Feb-afterplan-2017-low", "-")(2)

Answer 2

I'm not brilliant with RegEx so no doubt this can be improved.
As a worksheet function:
Public Function ConvertDate(sData As String) As Variant
Dim RE As Object, REMatches As Object
Dim Temp As String
Set RE = CreateObject("vbscript.regexp")
With RE
.MultiLine = False
.Global = False
.IgnoreCase = True
.Pattern = "\d{4}"
End With
Set REMatches = RE.Execute(sData)
If REMatches.Count > 0 Then
Temp = "1-" & Left(sData, 3) & "-" & REMatches(0)
ConvertDate = CDate(DateValue(Temp))
Else
'Returns #VALUE error on no match.
ConvertDate = CVErr(xlValue)
End If
End Function
Passes date by reference and returns TRUE/FALSE:
Public Sub Test()
Dim MyDate As Date
If ConvertDate1("Jan preplan-2017", MyDate) Then
MsgBox "Date converted to " & Format(MyDate, "dd-mmm-yy"), vbOKOnly
Else
MsgBox "Date not converted.", vbOKOnly
End If
End Sub
Public Function ConvertDate1(sData As String, ByRef ReturnValue As Date) As Boolean
Dim RE As Object, REMatches As Object
Dim Temp As String
Set RE = CreateObject("vbscript.regexp")
With RE
.MultiLine = False
.Global = False
.IgnoreCase = True
.Pattern = "\d{4}"
End With
Set REMatches = RE.Execute(sData)
If REMatches.Count > 0 Then
Temp = "1-" & Left(sData, 3) & "-" & REMatches(0)
ReturnValue = CDate(DateValue(Temp))
ConvertDate1 = True
Else
ConvertDate1 = False
End If
End Function
The RegEx can be improved to check first three letters are a month... loads can be done to improve, but you get the picture I hope.