ClickHouse supports the Projections mechanism to store data in a format that optimizes query execution. It allows using ALTER TABLE to manipulate projections: https://clickhouse.com/docs/en/sql-reference/statements/alter/projection. And I'm going to support those syntaxes for the ClickHouse parser, but to make PRs easier to review. I will separate them into three parts: 1. https://github.com/sqlparser-rs/sqlparser-rs/pull/1390 2. https://github.com/sqlparser-rs/sqlparser-rs/pull/1417 3. Add support of `PROJECTION column` when creating table for ClickHouse