Query iterator has unexpected side effects

[eugene-kulak]

Currently, if you call begin two or more times you will skip records as the cursor will be moved every time. This is not how begin should behave and definitely not what most people expect from. Typical use case - check if the result has any rows

qry.begin() != qry.end()

and then iterate

[iwongu]

It's unfortunate to have this limitation. I used the std::input_iterator_tag to tell that it's a single pass iterator.