我正在尝试获得两行的结果集。
这两行是在BETWEEN运算符中指定的时间跨度之间找到的最后一行。
如何实现这一结果？
以下代码不起作用。
SELECT
DaySum_1+DaySum_2+DaySum_3+DaySum_4+DaySum_5
AS october
FROM solarenergy
WHERE ((DatumUhrzeit BETWEEN '2014-10-01 01:00:00' AND '2014-10-01 23:00:00') LIMIT 1)
OR ((DatumUhrzeit BETWEEN '2014-10-02 01:00:00' AND '2014-10-02 23:00:00') LIMIT 1)
ORDER BY DatumUhrzeit DESC
答案 0 :(得分：1)
您需要执行UNION才能应用两个单独的LIMIT，因为每个查询只能使用一个LIMIT。要使用单个UNION子句，每个()组件必须包含在(
SELECT
DaySum_1+DaySum_2+DaySum_3+DaySum_4+DaySum_5 AS october
FROM solarenergy
WHERE DatumUhrzeit BETWEEN '2014-10-01 01:00:00' AND '2014-10-01 23:00:00'
ORDER BY DatumUhrzeit DESC
LIMIT 1
) UNION (
SELECT
DaySum_1+DaySum_2+DaySum_3+DaySum_4+DaySum_5 AS october
FROM solarenergy
WHERE DatumUhrzeit BETWEEN '2014-10-02 01:00:00' AND '2014-10-02 23:00:00'
ORDER BY DatumUhrzeit DESC
LIMIT 1
)
UNION如果您想保证()产生的两行订单，必须在最后(
SELECT
DaySum_1+DaySum_2+DaySum_3+DaySum_4+DaySum_5 AS october
FROM solarenergy
WHERE DatumUhrzeit BETWEEN '2014-10-01 01:00:00' AND '2014-10-01 23:00:00'
ORDER BY DatumUhrzeit DESC
LIMIT 1
) UNION (
SELECT
DaySum_1+DaySum_2+DaySum_3+DaySum_4+DaySum_5 AS october
FROM solarenergy
WHERE DatumUhrzeit BETWEEN '2014-10-02 01:00:00' AND '2014-10-02 23:00:00'
ORDER BY DatumUhrzeit DESC
LIMIT 1
)
/* Global ORDER BY after UNION */
ORDER BY october ASC
组之外应用
{{1}}