What happens if you run the following query?
SELECT YAB
FROM UD_Indiv_Data
WHERE YAB IS NOT NULL
AND TRY_CAST( YAB AS DATETIME) IS NULL;
If you get rows, then those rows are not valid dates.
Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?
How to post data/code on a forum to get the best help: Option 1 / Option 2