You can use SqlValidator.getFieldOrigins for a SqlNode, or use
RelMetadataQuery.getColumnOrigins for a RelNode.
- Jin
Julian Hyde <jh...@apache.org> 于2020年4月17日周五 上午7:29写道：
> At the RelNode level, you can use RelMetadataQuery.getColumnOrigins.
>
> But I’m sure that there’s something available at the SqlNode level, after
> validation. PreparedExplain.getFieldOrigins() is what the JDBC driver uses
> to provide ResultSetMetadata.getColumnName(int) etc.
>
> Julian
>
>
>
> > On Apr 16, 2020, at 4:17 PM, Feng Zhu <wellfeng...@gmail.com> wrote:
> >
> > You can customize a RelVisitor to visit the RelNode, and collect the
> > columns from TableScan's rowtype.
> >
> > 王驰 <wang...@kuaishou.com> 于2020年4月16日周四 下午11:23写道：
> >
> >> Hi folks,
> >>
> >>
> >> We're using CalCite in our project for SQL parsing and validating. We
> have
> >> a question: is there any way to get all used columns from a SQL?
> >>
> >>
> >> Consider the following case:
> >>
> >> we have two tables `user` and `user_region`. And the SQL is like
> >>
> >>
> >> ```
> >>
> >> SELECT
> >>
> >> id, name, age, country, province, city
> >>
> >> FROM
> >>
> >> user
> >>
> >> INNER JOIN user_region ON user.id = user_region.user_id
> >>
> >> WHERE age > 18;
> >>
> >> ```
> >>
> >>
> >> The result will be a Map with two keys:
> >>
> >>
> >> - 'user' --> List('id', 'name', 'age')
> >> - 'user_region' --> List('country', 'province', 'city', 'user_id')
> >>
> >>
> >> ======
> >>
> >> I've tried with SqlValidator (along with SqlValidatorScope,
> >> SqlValidatorNamespace) but found no easy ways to do this.
> >> I also tried to replay the validate process in our code but it seems
> >> impossible since most classes used are package private.
> >>
> >>
> >> Could you please give us some suggestions? Thanks!
> >>
> >>
>
>
