sql - 子查询作为联接?
问题描述
我的查询如下所示。
SELECT *,
SUM(A.money_step) over (
partition by A.id_key, A.P
ORDER BY A.actual_date
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
)as accumulated
FROM
(
SELECT A.*,
(
SELECT CASE WHEN COUNT(*) >= 2 THEN 2 ELSE 1 END
FROM example B
WHERE B.id_key = A.id_key
AND B.actual_date <= A.actual_date
AND attendance_status = 15
) P
FROM example A
)A
ORDER BY A.id_key,A.actual_date
是否可以将子查询表示为 FROM 子句中的连接?我使用“denodo”工具,我不能轻易地在 from 子句中执行子查询。
解决方案
您可以将您的子查询转移到 CTE,如下所示 -
WITH CTE AS
(
SELECT A.*,
(
SELECT CASE WHEN COUNT(*) >= 2 THEN 2 ELSE 1 END
FROM your_table B
WHERE B.id_key = A.id_key
AND B.actual_date <= A.actual_date
AND attendance_status = 15
) P
FROM your_table A
)
SELECT actual_date,id_key,attendance_status,money_step,
SUM(A.money_step) over (
partition by A.id_key, A.P
ORDER BY A.actual_date
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
)as accumulated
FROM CTE A
ORDER BY A.id_key,A.actual_date
您也可以将您的子查询直接放在分区部分的窗口函数中,如下所示 -
SELECT *,
SUM(A.money_step) over (
partition by A.id_key,(
SELECT CASE WHEN COUNT(*) >= 2 THEN 2 ELSE 1 END
FROM your_table B
WHERE B.id_key = A.id_key
AND B.actual_date <= A.actual_date
AND attendance_status = 15
)
ORDER BY A.actual_date
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
)as accumulated
FROM your_table A