Re: CAST(... ON DEFAULT) - WIP build on top of Error-Safe User Functions

On 2023-01-02 Mo 10:57, Tom Lane wrote:
> Corey Huinker <corey.huinker@gmail.com> writes:
>> The proposed changes are as follows:
>> CAST(expr AS typename)
>>     continues to behave as before.
>> CAST(expr AS typename ERROR ON ERROR)
>>     has the identical behavior as the unadorned CAST() above.
>> CAST(expr AS typename NULL ON ERROR)
>>     will use error-safe functions to do the cast of expr, and will return
>> NULL if the cast fails.
>> CAST(expr AS typename DEFAULT expr2 ON ERROR)
>>     will use error-safe functions to do the cast of expr, and will return
>> expr2 if the cast fails.
> While I approve of trying to get some functionality in this area,
> I'm not sure that extending CAST is a great idea, because I'm afraid
> that the SQL committee will do something that conflicts with it.
> If we know that they are about to standardize exactly this syntax,
> where is that information available?  If we don't know that,
> I'd prefer to invent some kind of function or other instead of
> extending the grammar.


+1


cheers


andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com