Support COMMENT before AS SELECT in CREATE MATERIALIZED VIEW

[sharadgaur]

Summary

ClickHouse's SHOW CREATE TABLE outputs COMMENT between the column list and AS SELECT for materialized views, but the parser only supported COMMENT after AS SELECT.

Before (fails)

CREATE MATERIALIZED VIEW db.mv TO db.target (a String) COMMENT 'test' AS SELECT a FROM db.src
-- Error: line X:0 <EOF> or ';' was expected, but got: "AS"

After (works)

Both positions are now supported:

• COMMENT before AS SELECT (SHOW CREATE TABLE format) ✅
• COMMENT after AS SELECT (documented syntax) ✅
• No COMMENT ✅

Change

Move the tryParseComment() call before the AS SELECT parsing, with a fallback to also try after AS SELECT if no comment was found before.

All existing tests pass.

Fixes #261

[chatgpt-codex-connector]

💡 Codex Review

clickhouse-sql-parser/parser/parser_table.go

Lines 671 to 675 in 365c90f

	name := &Ident{
	NamePos: p.last().Pos,
	NameEnd: p.last().End,
	Name: p.last().String,
	}

Preserve quote type for named table-arg identifiers

When building name := &Ident{...} for named parameters, the token’s QuoteType is dropped, so quoted keys are normalized to unquoted output. In cases where quoting is required (for example gcs(`my-key`='x')), String() emits my-key='x', which is not valid round-trip SQL and fails if reparsed because - is treated as an operator. Copy p.last().QuoteType (or parse via parseIdent) when constructing the parameter name.

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[git-hulk]

@sharadgaur Thanks for your improvement.