feat: Use string as default for unknown column type

[LeeMendelowitz]

PR for Issue #259.

Querying a JSON column on MySQL 8.0.26 returns a column of type 245, which is not handled by RMariaDB. This PR converts column of unknown type to string and issues a warning, which is similar to the RMySQL behavior.

[LeeMendelowitz]

@krlmlr I'm curious to hear what you think about this proposed solution whenever you have a chance.

[krlmlr]

Thanks, looks great!

[MichaelSchatz]

@krlmlr This would be a really helpful feature to have integrated into the package for a project I'm currently working on. Is there any chance of getting it merged into the next release candidate?

[krlmlr]

@LeeMendelowitz: warnings don't seem to be raised for MariaDB. What do you see when you run the following:

DBI::dbGetInfo(RMariaDB::mariadbDefault())$db.version
#> [1] "10.10.2-MariaDB"

^{Created on 2023-03-16 with reprex v2.0.2}

? I'd like to stabilize the tests before merging.

[krlmlr]

I added MySQL 8.0 configurations to main and merged it here, let's see what the tests say.

@LeeMendelowitz: can you please help by reporting what the following code shows on your system:

DBI::dbGetInfo(RMariaDB::mariadbDefault())$db.version
#> [1] "10.10.2-MariaDB"

[LeeMendelowitz]

@krlmlr Sorry for the delay. I get "5.5.5-10.11.2-MariaDB-1:10.11.2+maria~ubu2204".

For some reason RMariaDB::mariadbDefault()was not working for me when running off of the LeeMendelowitz:mysql8_json_support branch. I would get:

RMariaDB::mariadbDefault()
Error: Reason: Test database not available

It didn't seem to be using the [rs-dbi] group in my ~/.my.cnf, so I explicitly provided username + password + host + port instead.

[krlmlr]

Thanks!