Conversion of string to datetime fails with exception how to find which row causes it

Question

I'm currently importing some data from a very old database (access 2.0) into a sql server 2012 database. I imported all of the data (including the date field as it had values of 01.01.105 for 01.01.2005 ) into varchar fields.

Then I'm trying to import the data from the temporary table into the maintable. Until that point it all works as expected, but as soon as I started to import the data into the maintable (from the temptable) I ran into an error with the datetime field in the maintable.

I always get an error message there.

SQL The fields in mytemptable are (Nr - int and datum - varchar(50)) the fields in mymaintable (orderNo - int and orderDate - Datetime).

INSERT INTO mymaintable (orderNo, orderDate) SELECT
    Nr,
    TRY_PARSE(CASE WHEN len(datum) = 9
        THEN left(Datum,6) + CAST((CAST(right(Datum, 3) AS int) + 1900) AS varchar(4)) + ' 00:00:00.000'
        ELSE datum  + ' 00:00:00.000'
    END AS DATETIME USING 'de-DE') AS datum
FROM mytemptable;

Error message

Msg 6521, Level 16, State 1, Line 1 A .NET Framework error occurred during statement execution: System.Data.SqlTypes.SqlTypeException: SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM. System.Data.SqlTypes.SqlTypeException: at System.Data.SqlTypes.SqlDateTime.FromTimeSpan(TimeSpan value) at System.Data.SqlTypes.SqlDateTime.FromDateTime(DateTime value) at System.Data.SqlServer.Internal.CXVariantBase.DateTimeToSSDate(DateTime dt)

Additional infos

I tried only the select part with the same result, but another set of data (only 1k out of the 20k rows) functions without raising the error.

Edit: I tried to solve the problem with what was suggested in another post to use datetime2 instead of datetime and that functioned. BUT when I tried to find the rows that way by getting those where the datetime2 conversion returned null I received no result. Which means in essence DAtetime conversion fails, but datetime2 conversion does not fail at all.

Question

From what I saw (as I used it on a different part of the data already successfully) it seems not to be a general error, but one data related. So my question is there:

Is there any way of finding out which exactlyrow(s) is causing the problems?

(as I understood try_parse it should return null when a conversion error happens and NOT throw an exception)

Thanks

Answer 1

As datetime2 functions but datetime fails one must take into account that datetime is more restrictive than datetime2 in regards to dates. Thus by modifying the SQL select it can be found out easily where the error occurs:

 SELECT
    Nr,
    datum
FROM mytemptable
WHERE datum is not null and 
    TRY_PARSE(CASE WHEN len(datum) = 9
        THEN left(Datum,6) + CAST((CAST(right(Datum, 3) AS int) + 1900) AS varchar(4)) + ' 00:00:00.000'
        ELSE datum  + ' 00:00:00.000'
    END AS DATETIME2 USING 'de-DE') < '01.01.1753 00:00:00.000';

The "datum is not null" part has been added to make sure only "unknown" problem zones are found. If the above does not find any results, then the same should be made with the maximum date (instead of the minimum date) that datetime finds acceptable.

That way one can find out easily for which rows the conversion failed.