常用又偏门的sql

#1.根据时段统计数据

SELECT

CASE 
WHEN HOUR (create_date) BETWEEN 0 AND 12 THEN '00:00:00-12:00:00'
WHEN HOUR (create_date) BETWEEN 12 AND 14 THEN '12:00:00-14:00:00'
  ELSE
'其他时段'
  END 
  query_time,
  count(1)
FROM
adc_members
GROUP BY

query_time

#2.将查出一列自动变成,隔开的字符串

select group_concat(id) from adc_members