DOC: note about query strings in HDFStore selection

[cpcloud]

closes #6901

[cpcloud]

See #6901. That was the reported error, so I wanted to make that example explicit. It will fail with a syntax error if you interpolate the string into a query

[cpcloud]

I'll point out the single and double quote

[jreback]

maybe show that u can pass a string if u surround it with quotes

[cpcloud]

done

[cpcloud]

turning out to be more controversial than i would've expected

[jreback]

the locals interpolation is a bit magical (but useful)

I always use direct quotes -

[cpcloud]

speaking of that, i must've overlooked this when refactoring local vars API but shouldn't pytables follow that convention?

[jreback]

it should follow the same convention
problem?

[cpcloud]

i meant with the @ syntax. ... that doesn't seem to work

[cpcloud]

in the example from #6901

[jreback]

hmm
ok so is this more like eval or query?
it doesn't have context so maybe should be more like eval in that locals need @ ?

[cpcloud]

i'll make a new issue, merge this doc PR?

[jreback]

yep