数据库后端探测

select 'SQLite' where sqlite_version()
SELECT 'MySQL' FROM information_schema.ENGINES WHERE ENGINE='InnoDB' AND SUPPORT IN ('YES','DEFAULT') LIMIT 1;
SELECT 'PostgreSQL' WHERE current_setting('server_version') IS NOT NULL LIMIT 1;
SELECT 'SQL Server' where (select @@version) like '%SQL Server%'
SELECT 'Oracle' FROM all_users WHERE ROWNUM = 1
SELECT 'ClickHouse' WHERE uptime() > 0;
SELECT 'DuckDB' FROM duckdb_tables() LIMIT 1;