import java.sql.*;

/** 一次性只读探针：确认 H2(MySQL 模式) 支持哪些函数，决定方言测试需要补哪些别名。 */
public class H2Probe {
    public static void main(String[] args) throws Exception {
        try (Connection c = DriverManager.getConnection("jdbc:h2:mem:probe;MODE=MySQL;DATABASE_TO_LOWER=TRUE", "sa", "");
             Statement s = c.createStatement()) {
            probe(s, "if(1 = 1, 'a', 'b')");
            probe(s, "json_extract('{\"a\":1}', '$.a')");
            probe(s, "json_unquote('\"a\"')");
            probe(s, "lower(replace(cast('\"TRUE\"' as char), '\"', '')) in ('true')");
            probe(s, "greatest(3, 0)");
            probe(s, "coalesce(null, 1)");
            probe(s, "date_sub(now(), interval 20 second)");
        }
    }

    private static void probe(Statement s, String expression) {
        try (ResultSet r = s.executeQuery("select " + expression)) {
            r.next();
            System.out.println("OK   " + expression + "  =>  " + r.getObject(1));
        } catch (SQLException e) {
            System.out.println("FAIL " + expression + "  =>  " + e.getMessage().split("\n")[0]);
        }
    }
}