Support where, group by, having, order by clause without from clause in query statement.
For example as following:
SELECT 1 AS a, COUNT(), SUM(2), AVG(1), RANK() OVER() AS w_rank
WHERE 1 = 1
GROUP BY a, w_rank
HAVING COUNT() IN (1, 2) AND w_rank = 1
ORDER BY a;
this will return result:
| a |count(*)|sum(2)|avg(1)|w_rank|
+----+--------+------+------+------+
| 1 | 1| 2| 1.0| 1|
For another example as following:
select 1 c1, 2 union (select "hell0", "") order by c1
the second column datatype will be varchar(65533), 65533 is the default varchar length.
this will return result:
|c1 | 2 |
+------+---+
|1 | 2 |
|hell0 | |
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