MySql：這個查詢可以更有效嗎？

Question

我有一張名為TIMINGS的表

- - - - - - - - 創建 - - - - - - - -

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');

所以我想根據當前時間和下一個 TIMINGTYPE 知道 TIMINGTYPE

前任。 ：如果早餐開始和早餐結束之間的當前時間那么它應該返回'BREAKFAST'和下一個TIMINGTYPE

預期輸出例如：

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

所以我做了一個根據我的要求工作的查詢：

- - - - - - - - - - - 選擇 - - - - - - - - - - - - - - ——

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

---

所以我的問題是我可以讓它更有效率嗎？ 如果是，那么如何！

注意：我正在使用 MySql

任何幫助將不勝感激。 謝謝！

Answer 1

你可以這樣做：

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

邏輯是搜索正在進行或將來的記錄，然后按日期對其進行排序並保留最早的記錄。

請注意，使用current_time大大簡化了時間邏輯。

---

編輯

問題更新后：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)

如果您希望結果在同一行：

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