unique student number ADODC

good day everyone!
newbie in dbms abd vb here.,

i am having trouble automating student
number.,
i use this code to automate a unique student number.,

Code:

Dim uh As Integer uh = Data1.Recordset.RecordCount If uh = 0 Or uh < 10 Then MaskEdBox2.Text = "2009-000" & uh ElseIf uh = 10 And uh < 100 Then MaskEdBox2.Text = "2009-00" & uh ElseIf uh = 100 And uh < 1000 Then MaskEdBox2.Text = "2009-0" & uh ElseIf uh > 1000 And uh < 10000 Then MaskEdBox2.Text = "2009-" & uh Else MaskEdBox2.Text = "2009-" End If

now it does it job correctly..
but when i try to delete a record.,
lets say i have added records with student numbers from :
2009-0000,2009-0001,2009-0002,2009-0003,2009-0004

when i try to delete lets say 2009-0002
and tried to add another record the code brings the student number 2009-0004.,which should not because im trying to create a unique student number,.
the next studnumber should be 2009-0005.,

any help and explanation,.i'll be very thankful.,

thanks..