client: Make example testable

[dveeden]

This removes the client example from the README and puts it in its own file.

The benefits of this:

• This makes this a testable example
• This shows up in the godoc documentation

The drawbacks of this:

• It isn't in the README anymore
• This might be a bit weird for server examples that need the MySQL client. But there we could just have no output.

Issues found with the example while doing this:

1. Missing import for github.com/go-mysql-org/go-mysql/mysql (it uses mysql.FieldValueTypeFloat)
2. The example uses a table named table, which is confusing.
3. The example doesn't create the table
4. The defer r.Close() should probably be moved higher up
5. The r.GetInt() and r.GetIntByName() probably need more explanation
6. The test for the float type is never true
7. The values are never printed to standard out
8. The code doesn't run as it has an import, but the rest of the code isn't in a function as expected.
9. The r variable is created twice with :=
10. Not every result is closed
11. Error handling isn't done (Maybe that's ok or even desired for examples?)

Setting this as draft as I'm not sure if this is the right thing to do or not.

[lance6716]

rest lgtm

[dveeden]

This is how this looks with godoc:

Top part ↑

Bottom part ↓

So this only renders the contents of the Example function, not the context.

[dveeden]

This is after fixing the way I run godoc: (now the import is correct)

[lance6716]

Oh you mean the the purpose of Example is to improve godoc of this package? They are also runnable by go test -v ./client -run Example so I think we should also consider the friendly instruction when running it.

[lance6716]

Hi, do you need some help on this PR?

[dveeden]

Hi, do you need some help on this PR?

Still not 100% sure what the best way is. But I'm getting more sure that testable examples are the right choice.

[lance6716]

I have added my commit, PTAL @dveeden