多个字段取最大值、最小值、首个非空值

-- 多个值取最大和最小
select least(1,2,3,0,4,5) as min,greatest(1,2,3,0,4,5) as max;

+------+------+--+
| min  | max  |
+------+------+--+
| 0    | 5    |
+------+------+--+

select coalesce(null,null,1,null,0) as value1,coalesce(null,0) as value2,nvl(null,0) as value3;

+---------+---------+---------+--+
| value1  | value2  | value3  |
+---------+---------+---------+--+
| 1       | 0       | 0       |
+---------+---------+---------+--+