SQL中日期与字符串互相转换操作实例

select
      to_char(sysdate, 'yyyy') || '年' 
   || to_char(sysdate, 'mm') || '月' 
   || to_char(sysdate, 'dd') || '日'
   || ' '
   || to_char(sysdate, 'hh24') || '時' 
   || to_char(sysdate, 'mi') || '分' 
   || to_char(sysdate, 'ss') || '秒' 
from
  dual

select
  to_char(sysdate, 'yyyy-mm-dd hh24:mi:ss') 
from
  dual

select
  to_char(sysdate, 'yyyyfm-mm-dd hh24:mi:ss') 
from
  dual

select
  to_char(sysdate, 'yyyy/mm/dd') 
from
  dual

select
  to_char(sysdate, 'yyyymmdd') 
from
  dual

select
  to_date('20210908', 'yyyymmdd') 
from
  dual

select
  to_date('2021-9-8 11:21:55', 'yyyyfm-mm-dd hh24:mi:ss') 
from
  dual

SELECT
  CONVERT(varchar (100), GETDATE(), 111)

SELECT
  CONVERT(varchar (100), GETDATE(), 23)

SELECT
  CONVERT(varchar (100), GETDATE(), 112)

SELECT
  CONVERT(varchar (100), GETDATE(), 120)

select
    CONVERT(varchar, DATEPART(yy, GETDATE())) + '年' 
  + CONVERT(varchar, DATEPART(mm, GETDATE())) + '月' 
  + CONVERT(varchar, DATEPART(dd, GETDATE())) + '日'

SELECT
  CAST('20200908' as datetime)

SELECT
  CAST('20200908' as date)

SELECT 
  TRY_CAST('2021-09-08' as datetime)

SELECT 
  TRY_CAST('2021/09/08 11:21:55' as datetime)

SELECT
	DATE_FORMAT(NOW(), '%Y年%m月%d日 %H时%i分%s秒' );

SELECT
	DATE_FORMAT(NOW(), '%Y-%m-%d %H:%i:%s')

SELECT
	STR_TO_DATE('2019年01月17日 19时05分05秒', '%Y年%m月%d日 %H时%i分%s秒');