Question

我有两个表日志和学生在日志中我想选择stud_id＆＃39; s＆＃39; in＆＃39;和＆＃39; out＆＃39;在status_log中，状态为＆＃34; 0＆＃34;。如果stud_id进入和退出，则学生中的penalty_count正在增加。

日志

| stud_id | date_log  | time_log | ampm |status_log |status |
+---------+-----------+----------+------+-----------+-------+
| 123     |2015-08-19 | 07:38:34 | am   | in        | 0     |
| 123     |2015-08-19 | 07:40:34 | am   | out       | 0     |
| 5656    |2015-08-19 | 07:45:34 | am   | in        | 0     |
| 5656    |2015-08-19 | 07:47:34 | am   | out       | 0     |
| 56577   |2015-08-19 | 07:55:34 | am   | in        | 0     |
| 56577   |2015-08-19 | 07:59:34 | am   | out       | 1     |

如果学生进出的状态为＆＃34; 0＆＃34;则罚款将增加1。在状态。日志

|cardcode | name      | year |section    |penalty_count |
+---------+-----------+------+-----------+--------------+
| 123     |martin     | 1st  | A         | 0            |
| 5656    |neptali    | 1st  | A         | 0            |
| 56577   |juan       | 1st  | A         | 0            |

请帮助我thankyuo。

Answer 1

试试这样：

UPDATE student 
SET penalty=penalty + 1
WHERE cardcode IN (
  SELECT l1.stud_id FROM log AS l1
  JOIN log AS l2 ON l1.stud_id=l2.stud_id AND l2.status_log = 'out' AND l2.status = 0
  WHERE l1.status_log = 'in' AND l1.status = 0
  GROUP BY l1.stud_id
)

Answer 2

试试这个

UPDATE student SET penalty_count = (penalty_count + 1) 
WHERE cardcode IN 
(SELECT GROUP_CONCAT(stud_id) FROM log WHERE status_log = 'IN' AND status_log = 'OUT' 
AND status = 0 GROUP BY stud_id)

Answer 3

如果没有连接注释，也可以将此KEY(stud_id, status, status_log)添加到表日志中，以获得更好的性能。

update 
 penalty
set
  penalty_count = penalty_count + 1 
where 
 cardcode IN(
   select 
     stud_id
   from 
    log
   where 
    status = 0
   group by 
    stud_id
   having 
    (sum(status_log = 'in') + sum(status_log = 'out')) = 2
   order by 
    null
)

请注意，order by null是按功能禁用默认排序（解释输出中的filesort），因为您不需要在更新时对结果进行排序。

参见演示http://sqlfiddle.com/#!9/fb0dd

如果学生进出的状态为＆＃34; 0＆＃34;则罚款将增加1。处于状态

3 个答案: