IFNULL(exp1, exp2)
如果存在exp1则展示exp1，如果没有输出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
Logs,
( select @curNum := NULL, @counter := 0 ) as q
) as a
where
counter >= 3
https://www.cnblogs.com/dannylinux/articles/8288790.html