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.
[cid:e62a7598-728a-44d9-8e5c-365bdcde7c45]
Could you please give us some suggestions? Thanks!
