2019独角兽企业重金招聘Python工程师标准>>> 
对区间进行分组并且统计落在各区间内的数据量
主要使用 etl 和 INTERVAL 函数实现
mysql> select * from k1;
+------+------+
| id | yb |
+------+------+
| 1 | 100 |
| 2 | 11 |
| 3 | 5 |
| 4 | 501 |
| 5 | 1501 |
| 6 | 1 |
+------+------+现在要进行统计，小于100的，100~500的，500~1000的，1000以上的，这各个区间的id数
利用interval划出4个区间
再利用elt函数将4个区间分别返回一个列名
mysql> select elt(interval(d.yb,0, 100, 500, 1000), 'less100', '100to500', '500to1000', 'more1000') as yb_level, count(d.id) as cnt
-> from k1 d
-> group by elt(interval(d.yb, 0, 100, 500, 1000), 'less100', '100to500', '500to1000', 'more1000K');
+-----------+-----+
| yb_level | cnt |
+-----------+-----+
| 100to500 | 1 |
| 500to1000 | 1 |
| less100 | 3 |
| more1000 | 1 |
+-----------+-----+
4 rows in set (0.00 sec)如果需要按从小到大排序的话 可以在列名定义时稍加一个首字符 对各档区间进行排序
mysql> select elt(interval(d.yb,0, 100, 500, 1000), '1/less100', '2/100to500', '3/500to1000', '4/more1000') as yb_level, count(d.id) as cnt
-> from k1 d
-> group by elt(interval(d.yb, 0, 100, 500, 1000), '1/less100', '2/100to500', '3/500to1000', '4/more1000K');
+-------------+-----+
| yb_level | cnt |
+-------------+-----+
| 1/less100 | 3 |
| 2/100to500 | 1 |
| 3/500to1000 | 1 |
| 4/more1000 | 1 |
+-------------+-----+
4 rows in set (0.00 sec)