Microsoft Visual Studio 2017 - 在文本框中自动生成 ID

Question

I would like to add details to my table (sales table) where the sales ID starts from "SS1" and increments after each update. How do I code such that the vb does not crash when the table is still empty?

Private Function generate_id() As String
    '   Dim lastid As String = run_sql_query("SELECT MAX(FLD_ORDER_ID) AS LASTID FROM TBL_ORDER_A167640").Rows(0).Item("LASTID")
    '  Dim newid As String = "OR" & Mid(lastid, 3) + 1
    'Return newid
End Function

The code inserted will crash if the table is empty for say I wish to start from SS1. Please help ! :(

Answer 1

If I'm not wrong in what you want, a way to do that might be:

Private Function generate_id() As String
        Dim lastid As Integer = CInt(run_sql_query("SELECT COUNT(FLD_ORDER_ID) AS LASTID FROM TBL_ORDER_A167640").Rows(0).Item("LASTID")) + 1
        Return "S1_" & CStr(lastid)
End Function

However is better to use an autoincremental ID/index as prefix numeric for your new id after “S1_”. Like this “S1_” & Select MAX( [autoncrementalID] ) as NUMID ....