time_zone DSN parameter value requires quoting

[dolmen]

To set the time_zone from the DSN, the value must be quoted. But this is not correctly documented.

Examples (named time zone really work only if the time_zone tables exists on the server):

Wanted value	Fails	Works
+00:00	&time_zone=%2B00%3A00	&time_zone=%27%2B00%3A00%27
UTC	&time_zone=UTC	&time_zone=%27UTC%27
Europe/Paris	&time_zone=Europe%2FParis	&time_zone=%27Europe%2FParis%27

I suppose the same issue will happen for any session parameter that is of type string.

I find that using quoting in counter-intuitive, so I'm not sure if this is that the documentation that should be fixed.

[julienschmidt]

Right below: "The values must be url.QueryEscape'ed!"

[julienschmidt]

Sorry, quoted not escaped. That was a little too fast..

[julienschmidt]

Even though it feels unnatural, I don't think there is much we can do about it.
Keeping a list of all variables that need to be quoted is certainly not an option.

So we have to fix the documentation. Any suggestions how to phrase it?

[arnehormann]

How about https://github.com/go-sql-driver/mysql/blob/master/connection.go#L55 -> err = mc.exec("SET " + param + "=\"" + strconv.Quote(val) + "\"") (just with an alternative to Quote hitting all must-be-escaped MySQL chars).
MySQL extracts the relevant type from a string anyway...

[dolmen]

@arnehormann Too late. Code in the wild is already relying on the existing behaviour. That's what happens when issues are reviewed 10 months after the report.

I'm writing a documentation patch.

[arnehormann]

@dolmen we can also detect if it starts quoted and only apply this otherwise...

[dolmen]

@arnehormann a full fix would also have to take care of also handling quotes quoted inside the value.
proxy_user=%27abc%27%27def%27 for SET proxy_user='abc''def' to set value abc'def
(I don't have access to a MySQL db now to check this is valid syntax)

[arnehormann]

as I said: just with an alternative to Quote hitting all must-be-escaped MySQL chars
See http://dev.mysql.com/doc/refman/5.7/en/string-literals.html#character-escape-sequences