The other probleme in Calibre by using custom columns is, that a "show metadata" window, what was very informative, when I started to use Calibre, now became an absolutely chaos. It shows all custom columns (and in not reorderable way...), but most of them are only technical datas, not for human eyes.
From programing and data managing tools I am familiar only with PHP and MySQL. If compare them with Calibre, I must to say: for the price of ~5× more complicated solutions of Calibre we get ~5% of the power of PHP+MySQL.
Or, other example: as I wrote in other subforum, for managing my musics' metadatas, I use german program Mp3tag. Its (and similar foobar2000 player's) managing ability, with clear, nesteable ans easy understandable functions, actions, exports -- if compare with Calibre...
- I simply can not understand, why I must to create lately not manageable "columns" for a simple task: to show metadata in modified way (replace, and so on).
- I simply can not understand, why I must to create more new columns for a simple task: to nest a functions.