php - Mysql查询CONCAT改变输出

Question

我有以下查询:

mysql> select (select m.delay from messages m order by message_id desc limit 1) as Delay, s.min_delay, s.max_delay from statistics s order by s.date_hour desc limit 1;
+-------+-----------+-----------+
| Delay | min_delay | max_delay |
+-------+-----------+-----------+
|    10 |      7.00 |     12.00 |
+-------+-----------+-----------+
1 row in set (0.00 sec)

这很好。但我需要得到以下格式的结果:

 Delay=10 Min_Delay=7.00 Max_Delay=12.00

我可以使用 concat 来做到这一点吗？

Answer 1

通常，您会在应用层进行转换。但是，如果你想使用 concat()，你可以在 MySQL 中完成:

select concat_ws(' ',
                 concat('Delay=', (select m.delay from messages m order by message_id desc limit 1)),
                 concat('Min_Delay=', s.min_delay),
                 concat('Max_Delay=', s.max_delay)
                )
from statistics s
order by s.date_hour desc
limit 1