I'm really new to ASP.net and I am currently trying to create a registration page on a site. I was successful in adding a user to the database but I decided to add another feature into the code to check what userID's were available. For example, if a user deleted their account their userID would become available for use again. I'm trying to find the min value and the max value and add or subtract 1 depending on whether it is min or max. I can run the code I have written for this with no errors but the user is not added to the database. Can anyone help me figure out what I'm missing from my code to do this?

EDIT >>>>> Code adds a user to database but it adds the new user at -1 instead. I don't seem to be able to see where the issue is.

If (aDataReader2.Read() = False) Then
  aConnection1 = New OleDbConnection(aConnectionString)
  aConnection1.Open()
  aQuery = "Insert Into UserDetails "
  aQuery = aQuery & "Values ('" & userID & "','" & userFName & "','" & userLName & "','" & userEmail & "','" & userUsername & "','" & userPassword & "')"
  aCommand = New OleDbCommand(aQuery, aConnection1)
  aCommand.ExecuteNonQuery()
  aConnection1.Close()
ElseIf (min = 1) Then
  aConnection2 = New OleDbConnection(aConnectionString)
  aConnection2.Open()
  aCommand = New OleDbCommand(aQuery3, aConnection2)
  aDataReader2 = aCommand.ExecuteReader()
  userID = max + 1
  aQuery = "Insert Into UserDetails "
  aQuery = aQuery & "Values ('" & userID & "','" & userFName & "','" & userLName & "','" & userEmail & "','" & userUsername & "','" & userPassword & "')"
  aCommand = New OleDbCommand(aQuery, aConnection2)
  aCommand.ExecuteNonQuery()
  aConnection2.Close()
Else
  aConnection3 = New OleDbConnection(aConnectionString)
  aConnection3.Open()
  aCommand = New OleDbCommand(aQuery2, aConnection3)
  aDataReader2 = aCommand.ExecuteReader
  userID = min - 1
  aQuery = "Insert Into UserDetails "
  aQuery = aQuery & "Values ('" & userID & "','" & userFName & "','" & userLName & "','" & userEmail & "','" & userUsername & "','" & userPassword & "')"
  aCommand = New OleDbCommand(aQuery, aConnection3)
  aCommand.ExecuteNonQuery()
  aConnection3.Close()
  lblResults.Text = "User Account successfully created"
  btnCreateUser.Enabled = False
End If

Here's the code I used to get the max and min values from the database. I'm getting a value of 0 for both of them - when min should be 1 and max should be 5

 Dim minID As Integer
 Dim maxID As Integer
 aQuery2 = "Select Min(UserID) AS '" & [minID] & "' From UserDetails"
 aQuery3 = "Select Max(UserID) AS ' " & [maxID] & "' From UserDetails"