MySql：这个查询可以更有效吗？

Question

我有一张名为TIMINGS的表

- - - - - - - - 创建 - - - - - - - -

CREATE TABLE TIMINGS(
    SNO TINYINT UNIQUE NOT NULL AUTO_INCREMENT,
    TIMINGTYPE VARCHAR(20) PRIMARY KEY,
    STARTTIME TIME NOT NULL,
    ENDTIME TIME NOT NULL
)

- - - - - - - - - 插入 - - - - - - - - - - -

INSERT INTO TIMINGS(TIMINGTYPE, STARTTIME, ENDTIME) VALUES
('BREAKFAST','08:34:00','10:00:00'),
('LUNCH','11:30:00','13:30:00'),
('DINNER','19:00:00','20:30:00');

所以我想根据当前时间和下一个 TIMINGTYPE 知道 TIMINGTYPE

前任。 ：如果早餐开始和早餐结束之间的当前时间那么它应该返回'BREAKFAST'和下一个TIMINGTYPE

预期输出例如：

----------------------------------------------------------
     CURRENTTIME   |     NEXT
-----------------------------------------------------------
1.  BREAKFAST        |      LUNCH
-----------------------------------------------------------

所以我做了一个根据我的要求工作的查询：

- - - - - - - - - - - 选择 - - - - - - - - - - - - - - ——

SELECT (
 CASE
    WHEN DATE_FORMAT(CONVERT_TZ(NOW(),'+00:00','+05:30') ,'%H:%i:%s' ) BETWEEN (select STARTTIME from TIMINGS where TIMINGTYPE = 'BREAKFAST') AND (select ENDTIME from TIMINGS where TIMINGTYPE = 'BREAKFAST') THEN 'BREAKFAST'    
    WHEN DATE_FORMAT(CONVERT_TZ(NOW(),'+00:00','+05:30') ,'%H:%i:%s' ) BETWEEN (select STARTTIME from TIMINGS where TIMINGTYPE = 'LUNCH') AND (select ENDTIME from TIMINGS where TIMINGTYPE = 'LUNCH') THEN 'LUNCH'
    WHEN DATE_FORMAT(CONVERT_TZ(NOW(),'+00:00','+05:30') ,'%H:%i:%s' ) BETWEEN (select STARTTIME from TIMINGS where TIMINGTYPE = 'DINNER') AND (select ENDTIME from TIMINGS where TIMINGTYPE = 'DINNER') THEN 'DINNER'
    ELSE 'NOT AVAILABLE'
 END
) as CURRENTTIME, 
(
 CASE
    WHEN DATE_FORMAT(CONVERT_TZ(NOW(),'+00:00','+05:30') ,'%H:%i:%s' ) BETWEEN (select ENDTIME from TIMINGS where TIMINGTYPE = 'BREAKFAST') AND (select STARTTIME from TIMINGS where TIMINGTYPE = 'LUNCH') THEN 'LUNCH'

    WHEN DATE_FORMAT(CONVERT_TZ(NOW(),'+00:00','+05:30') ,'%H:%i:%s' ) BETWEEN (select ENDTIME from TIMINGS where TIMINGTYPE = 'LUNCH') AND (select STARTTIME from TIMINGS where TIMINGTYPE = 'DINNER') THEN 'DINNER'

    ELSE 'BREAKFAST'
 END) as NEXT

---

所以我的问题是我可以让它更有效率吗？ 如果是，那么如何！

注意：我正在使用 MySql

任何帮助将不胜感激。 谢谢！

Answer 1

你可以这样做：

select t.*
from timings t
where 
    (current_time between starttime endtime)    -- on-going
    or (current_time >= endttime)               -- next
order by starttime
limit 1

逻辑是搜索正在进行或将来的记录，然后按日期对其进行排序并保留最早的记录。

请注意，使用current_time大大简化了时间逻辑。

---

编辑

问题更新后：您可以使用union all ：

-- on-going
(select 'current', timingtype from timings where current_time between starttime and endtime)
union all
-- upcoming
(select 'upcomong', timingtype from timings where current_time > endtime order by starttime limit 1)

如果您希望结果在同一行：

select 
    (select timingtype from timings where current_time between starttime and endtime) current,
    (select timingtype from timings where current_time > endtime order by starttime limit 1) upcoming