IFNULL(exp1, exp2)

如果存在exp1則展示exp1，如果沒有輸出exp2

cast

convert

# Write your MySQL query statement below
select DISTINCT
Num as ConsecutiveNums
from
(
select
Num,
( CASE WHEN Num = @curNum THEN @counter := @counter + 1 WHEN @curNum :=Num THEN @counter := 1 END ) as counter
from

https://www.cnblogs.com/dannylinux/articles/8288790.html

【leetcode刷題】mysql題庫