bug: parser fails on CREATE MATERIALIZED VIEW with COMMENT before AS SELECT

[sharadgaur]

Problem

The parser fails when COMMENT appears between the column list and AS SELECT in a CREATE MATERIALIZED VIEW statement. This is the exact format ClickHouse returns from SHOW CREATE TABLE.

Reproducer

-- This FAILS:
CREATE MATERIALIZED VIEW db.mv TO db.target
(
    `a` String,
    `b` Int64
)
COMMENT 'some comment'
AS SELECT a, b FROM db.src

Error: line 6:0 <EOF> or ';' was expected, but got: "AS"

Expected

Should parse successfully. ClickHouse outputs this exact format from SHOW CREATE TABLE for any MV that has a COMMENT set.

Root Cause

In parser_view.go, the parser tries COMMENT only after AS SELECT:

if p.tryConsumeKeywords(KeywordAs) { ... }
comment, err := p.tryParseComment()  // only here, after AS SELECT

But ClickHouse's SHOW CREATE TABLE outputs COMMENT before AS SELECT. The parser sees COMMENT where it expects AS or EOF, and fails.

Fix

Try parsing COMMENT both before and after AS SELECT to handle both the documented syntax and the SHOW CREATE TABLE output format.

[sharadgaur]

Verified against ClickHouse

Tested on actual ClickHouse clusters:

ClickHouse Version	SHOW CREATE TABLE COMMENT position
25.8.10.7	COMMENT after AS SELECT
26.2.4.23	COMMENT before AS SELECT

The COMMENT position in SHOW CREATE TABLE output changed between ClickHouse versions. The parser needs to support both positions.

ClickHouse does not support COMMENT in the CREATE syntax directly — it's always set via ALTER TABLE MODIFY COMMENT. The SHOW CREATE TABLE output format is what varies.

-- 25.8 output:
CREATE MATERIALIZED VIEW db.mv TO db.dst (a String)
AS (SELECT a FROM db.src)
COMMENT 'test'

-- 26.2 output:
CREATE MATERIALIZED VIEW db.mv TO db.dst (a String)
COMMENT 'test'
AS SELECT a FROM db.src

The fix in PR #262 handles both positions correctly.