The prepareSql function quotes any word not in SQL_KEYWORDS as an
identifier. Since AT and ZONE were missing from the set, the expression
(NOW() AT TIME ZONE 'UTC') was mangled into (NOW() "AT" TIME "ZONE"
'UTC'), causing INSERT failures on PostgreSQL.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add three SqlDialect implementations with a factory function:
- MySqlDialect: positional ?, ON DUPLICATE KEY UPDATE, LIMIT/OFFSET
- SqlServerDialect: @pN params, MERGE USING, OFFSET/FETCH
- PostgreSqlDialect: $N (1-based), ON CONFLICT DO UPDATE, LIMIT/OFFSET
TDD approach: 43 tests written first, all passing.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>