开发常用代码区

1. 查询两个LocalDate类型之间的所有日（周，月）

long numOfDays = ChronoUnit.WEEKS.between(startDateLocal, endDateLocal);
List<LocalDate> dateList = LongStream.range(0, numOfDays).mapToObj(startDateLocal::plusWeeks)//映射.collect(Collectors.toList());//收集

2. Date类型转LocalDate

LocalDate startDateLocal = startDate.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

3. 字符串（单个或多个）转List

List<String> list = Arrays.asList("aaa","bbb");

4. 用mysql查询笛卡尔积

select * from
(select a.c1,a.c2,a.c3 from a) e
CROSS JOIN 
(select b.d1,b.d2,b.d3 from b) f

5. mysql使用case…when

select 
case a.a1 when '0' then '就是0' 
else '就是1' end
from a