Question

我有一个表refill_roster，每天有3个时段

mysql> select day,slot1,slot2,slot3 from location_refill_roster;
+------+----------+----------+----------+
| day  | slot1    | slot2    | slot3    |
+------+----------+----------+----------+
|    1 | 14:45:22 | 14:45:24 | 14:45:25 |
|    2 | 14:45:22 | 14:45:24 | 14:45:25 |
|    3 | 14:45:22 | 14:45:24 | 14:45:25 |
|    4 | 14:45:22 | 14:45:24 | 14:45:25 |
|    5 | 14:45:22 | 14:45:34 | 14:45:25 |
|    6 | 14:45:22 | 14:45:24 | 14:45:25 |
|    7 | 09:45:22 | 11:45:28 | 12:45:25 |
+------+----------+----------+----------+

我想在某个时间点找到当天的下一个时段。例如，在第7天的10:00:00，下一个可用的插槽应该是slot2，即11:45:28。

无法找到将数字与多列进行比较的方法。所以我转换了表并写了一个子查询进行比较。有没有更好的方法来实现解决方案

SELECT slots,
       MAX(CASE WHEN day = '1' THEN value END) `1`,
       MAX(CASE WHEN day = '2' THEN value END) `2`,
       MAX(CASE WHEN day = '3' THEN value END) `3`,
       MAX(CASE WHEN day = '4' THEN value END) `4`,
       MAX(CASE WHEN day = '5' THEN value END) `5`,
       MAX(CASE WHEN day = '6' THEN value END) `6`,
       MAX(CASE WHEN day = '7' THEN value END) `7`
FROM
(
 SELECT day, slots,
     CASE slots 
        WHEN 'slot1' THEN slot1
        WHEN 'slot2' THEN slot2
        WHEN 'slot3' THEN slot3
     END value
FROM refill_roster t CROSS JOIN
  (
    SELECT 'slot1' slots UNION ALL
    SELECT 'slot2' UNION ALL
    SELECT 'slot3' 
  ) c where t.day=7
) q 
 GROUP BY slots
 ORDER BY FIELD(slots, 'slot1', 'slot2', 'slot3')

Answer 1

请考虑以下事项：

DROP TABLE IF EXISTS my_table;

CREATE TABLE my_table
(day INT NOT NULL
,slot INT NOT NULL
,time TIME NOT NULL
,PRIMARY KEY(day,slot)
);

INSERT INTO my_table VALUES
(1,1,'14:45:22'),
(2,1,'14:45:22'),
(3,1,'14:45:22'),
(4,1,'14:45:22'),
(5,1,'14:45:22'),
(6,1,'14:45:22'),
(7,1,'09:45:22'),
(1,2,'14:45:24'),
(2,2,'14:45:24'),
(3,2,'14:45:24'),
(4,2,'14:45:24'),
(5,2,'14:45:34'),
(6,2,'14:45:24'),
(7,2,'11:45:28'),
(1,3,'14:45:25'),
(2,3,'14:45:25'),
(3,3,'14:45:25'),
(4,3,'14:45:25'),
(5,3,'14:45:25'),
(6,3,'14:45:25'),
(7,3,'12:45:25');

SELECT * 
  FROM my_table 
 WHERE day = 7 
   AND time > '10:00:00' 
 ORDER 
    BY slot 
 LIMIT 1;

  +-----+------+----------+
  | day | slot | time     |
  +-----+------+----------+
  |   7 |    2 | 11:45:28 |
  +-----+------+----------+
  1 row in set (0.00 sec)

Answer 2

我不是MySQL用户，但这就是我接近它的方式。如果我提出MySQL不能做的事情，我相信其他人可以纠正我。

我假设那天（1-7）是一个参数，所以我称之为@day。我还假设您想要比较的时间是@currentTime。

我也假设slot1 <= slot2 <= slot3。如果情况并非总是如此，那么这将变得更加复杂。

 select  case when @currentTime <= slot1 then slot1
              when @currentTime <= slot2 then slot2
              when @currentTime <= slot3 then slot3
              else null
         end as [NextSlot]
 from    refill_roster rr
 where   rr.day = @day

将数字与mysql中的多个列进行比较

2 个答案: