Re: AWS forcing PG upgrade from v9.6 a disaster

On 2021-05-29 13:35, Andrew Dunstan wrote:
> On 5/29/21 3:59 PM, Dean Gibson (DB Administrator) wrote:
>> Meanwhile, I've been doing some checking.  If I remove "CAST(
>> license_status AS CHAR ) = 'A'", the problem disappears.  Changing the
>> JOIN to a RIGHT JOIN, & replacing WHERE with ON, also "solves" the
>> problem, but there is an extra row where license_status is NULL, due
>> to the RIGHT JOIN.  Currently trying to figure that out (why did the
>> CAST ... match 'A', if it is null?)...
> Why are you using this expression? It's something you almost never want
> to do in my experience. Why not use the substr() function to get the
> first character?
>
> cheers
>
> andrew
>
> --
> Andrew Dunstan
> EDB: https://www.enterprisedb.com

Although it doesn't matter in this case, I do it because in general, it
changes the type of the value from CHAR to bptext or whatever it is, &
that has causes comparison issues in the past.  It's just a matter of
habit for me when working with CHAR() types.

But this case, where it doesn't matter, I'd use LEFT().