sql - 在DB2中选择今年的第一天和最后一天

Question

如何在 DB2 中以 YYYYMMDD 格式获取当年的第一天和最后一天？

我试过:

SELECT SUBSTR(CHAR(CURRENT DATE),8,0)||'0101' 

和:

SELECT SUBSTR(CHAR(CURRENT DATE),8,0)||'1231

但是在我输入年份之前它不起作用，但我需要将年份作为参数“不需要每年在查询中更改它”

Answer 1

你可以这样做:

select
    date('0001-01-01') + year(current date) years - 1 year first_day_of_the_year,
    date('0001-01-01') + year(current date) years - 1 day  last_day_of_the_year
from sysibm.sysdummy1

Demo on DB Fiddle :

FIRST_DAY_OF_THE_YEAR | LAST_DAY_OF_THE_YEAR
--------------------: | -------------------:
           2020-01-01 |           2020-12-31

If you want the results as strings in YYYYMMDD format, you can format the results with to_char():

select
    to_char(date('0001-01-01') + year(current date) years - 1 year, 'yyyymmdd') first_day_of_the_year,
    to_char(date('0001-01-01') + year(current date) years - 1 day, 'yyyymmdd')  last_day_of_the_year
from sysibm. sysdummy1