select the last OrderId value then + 1.
ex : 1,2,3
Select last value = 3, then 3 + 1 = 4...

Or u can set data types as AutoNumber

it wont be a problem if your using bindingsource

Hi friend ..
just imagin ur table orderid is ur column name ok so just write follwoing code.

public sub Form_Load()

Dim cmd as new OledbCommand("Select * from TableName",cn) 'cn is Connection Object

cn.open()

Dim dr as oledbdatareader=cmd.executereader

while dr.read()
TextBox1.Text=dr(0)
End While

TextBox1.Text=Val(TextBox1.Text) + 1
dr.close()
cn.close()

End Sub