Even with newer version of SQL being stricter on mixing "union" statements such as

select 7 union select 'A', the original explation is not adequite to say the least.

If that is all the problem, then there is no need to have the follow-up select statements.

The fact is, if you work around the new "union" feature/bug, by breaking the insertion to 2 parts - select 1 union 2... and select "A" union select "B", you have all items inserted into the table. Then, you still likely get an error running the follow-up select statements - I did.

Regardless the select SQL executed with error or without error, the explanation is based on how SQL interprates those select SQL statements - that clearly is not universally the same as we can be seen by different posts.

In my case, SQL is doing a "implicit conversion" on Col to compare with 1 and 6, therefor it fails for values such as "A".

If I change the filter condition from Between 1 and 6 -> Between '1' and '6', it runs with out errors.