VB - Einfache Ähnlichkeitssuche (SQL)

''' <summary>
''' Erzeugt aus einem String einen Suchstring der ähnliche Ergebisse findet
''' </summary>
''' <param name="str">Suchstring</param>
''' <param name="EnclosingTags">Soll der String ein führendes und folgendes % haben?</param>
''' <returns>Konvertierter Suchstring</returns>
''' <remarks>Ersetzt Sonderzeichen mit % und setzt ein % zwischen Ziffern/Buchstaben</remarks>
Public Function CreateSimilarSearchString(ByVal str As String, Optional ByVal EnclosingTags As Boolean = False) As String
	Dim numbers() As String = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9"}
	Dim IsNumber As Boolean
	Dim tmp As String = ""

	str = FindAndReplace(str, " ", "%", False)
	str = FindAndReplace(str, "-", "%", False)
	str = FindAndReplace(str, "_", "%", False)
	str = FindAndReplace(str, ".", "%", False)
	str = FindAndReplace(str, ",", "%", False)
	str = FindAndReplace(str, "+", "%", False)
	str = FindAndReplace(str, "(", "%", False)
	str = FindAndReplace(str, ")", "%", False)
	str = FindAndReplace(str, "*", "%", False)
	str = FindAndReplace(str, "'", "%", False)
	CreateSimilarSearchString = ""

	If Len(str) > 1 Then
		tmp = Mid(str, 1, 1)
		If ArrExist(numbers, Mid(str, 1, 1), False) > -1 Then
			IsNumber = True
		Else
			IsNumber = False
		End If

		For i = 2 To Len(str)
			If ArrExist(numbers, Mid(str, i, 1), False) > -1 Then
				If IsNumber = False Then
					tmp += "%" & Mid(str, i, 1)
					IsNumber = True
				Else
					tmp += Mid(str, i, 1)
				End If
			Else
				If IsNumber = True Then
					tmp += "%" & Mid(str, i, 1)
					IsNumber = False
				Else
					tmp += Mid(str, i, 1)
				End If
			End If
		Next
	End If
	If EnclosingTags = True Then tmp = "%" & tmp & "%"
	CreateSimilarSearchString = tmp
End Function