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Old April 8th, 2004, 02:27 PM
gylim78 gylim78 is offline
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Default Problem converting type

Hi all,

   Got a very simple task to do, but I have not been able to get it done. It is driving me crazy !!!

   I am doing a invoice sw. I need to pull out the last invoice number(ie the largest number) from the db, and add 1 to it to generate the next invoice number. So far, I have had no problem retriving the last invoice number from the db into a dataset. But when I try to add 1 to it ... it gives me the error "System.InvalidCastException: Cast from type 'DBNull' to type 'Integer' is not valid."

    My code is as follows :
    dim tmp_inv_no2 as integer
    ds = SelectRows(ds,inv_conn_str,mysql,"inv")
    tmp_inv_no2 = ds.tables("inv").compute("MAX(inv_no)","")
    inv_no.text = tmp_inv_no2

But when I changed my code to the following ...
    dim tmp_inv_no2 as string
    ds = SelectRows(ds,inv_conn_str,mysql,"inv")
    tmp_inv_no2 = ds.tables("inv").compute("MAX(inv_no)","").tostrin g()
    inv_no.text = tmp_inv_no2

I can display the last invoice number with no problem !! Therefore, it is not a NULL value.

I next tried to convert the string to a integer by using the following code ...

    dim tmp_inv_no2 as string
    dim tmp_inv_no3 as integer
    ds = SelectRows(ds,inv_conn_str,mysql,"inv")
    tmp_inv_no2 = ds.tables("inv").compute("MAX(inv_no)","").tostrin g()
    tmp_inv_no3 = cint(tmp_inv_no2)

I get an error message
System.FormatException: Input string was not in a correct format.

Please help

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