dongyan

Support named capture groups

26

This PR tries to support named capture groups. Closes #5, closes #102. ### Usages In the example ``` ocaml (Plus '0'..'9') as digits ``` Variable `digits` is defined as a...

## Feature Request **Is your feature request related to a problem? Please describe:** TiDB doesn't support `UNION` expressions inside subquery in select fields. ``` mysql select ((select count(a)) union (select...