配置單元日期字符串驗證

Question

我想檢查一個字符串是否有效的日期格式'YYYYMMDD'。

我正在使用以下技術。但是對於無效的日期字符串，我得到有效的日期結果。

我在做什麼錯？所有的

SELECT'20019999',CASE WHEN unix_timestamp('20019999','YYYYMMDD') > 0 THEN 'Good'ELSE 'Bad'END; 

Answer 1

首先，你使用了錯誤的格式

select from_unixtime(unix_timestamp())     as default_format 
     ,from_unixtime(unix_timestamp(),'YYYY-MM-DD') as wrong_format 
     ,from_unixtime(unix_timestamp(),'yyyy-MM-dd') as right_format 
; 

---

+----------------------+---------------+---------------+ 
| default_format | wrong_format | right_format | 
+----------------------+---------------+---------------+ 
| 2017-10-07 04:13:26 | 2017-10-280 | 2017-10-07 | 
+----------------------+---------------+---------------+ 

---

第二，有沒有驗證日期部分的範圍。
如果您將日期部分增加1，它會將您轉移到第二天。

with t as (select stack(7,'27','28','29','30','31','32','33') as dy) 
select t.dy 
     ,from_unixtime(unix_timestamp(concat('2017-02-',t.dy),'yyyy-MM-dd'),'yyyy-MM-dd') as dt 

from t 
; 

---

+-----+-------------+ 
| dy |  dt  | 
+-----+-------------+ 
| 27 | 2017-02-27 | 
| 28 | 2017-02-28 | 
| 29 | 2017-03-01 | 
| 30 | 2017-03-02 | 
| 31 | 2017-03-03 | 
| 32 | 2017-03-04 | 
| 33 | 2017-03-05 | 
+-----+-------------+ 

如果增加1月份部分其轉發您到下個月。

with t as (select stack(5,'10','11','12','13','14') as mn) 
select t.mn 
     ,from_unixtime(unix_timestamp(concat('2017-',t.mn,'-01'),'yyyy-MM-dd'),'yyyy-MM-dd') as dt 

from t 
; 

---

+-----+-------------+ 
| mn |  dt  | 
+-----+-------------+ 
| 10 | 2017-10-01 | 
| 11 | 2017-11-01 | 
| 12 | 2017-12-01 | 
| 13 | 2018-01-01 | 
| 14 | 2018-02-01 | 
+-----+-------------+ 

即使CAST有效性驗證只在部分範圍，而不是日期本身來完成。

select cast('2010-02-32' as date); 

---

+-------+ 
| _c0 | 
+-------+ 
| NULL | 
+-------+ 

---

select cast('2010-02-29' as date); 

---

+-------------+ 
|  _c0  | 
+-------------+ 
| 2010-03-01 | 
+-------------+ 

---

這裏才達到你的目標的方式：

with t as (select '20019999' as dt) 
select dt 
     ,from_unixtime(unix_timestamp(dt,'yyyyMMdd'),'yyyyMMdd') as double_converted_dt  

     ,case 
      when from_unixtime(unix_timestamp(dt,'yyyyMMdd'),'yyyyMMdd') = dt 
      then 'Good' 
      else 'Bad' 
     end    as dt_status 

from t 
; 

---

+-----------+----------------------+------------+ 
| dt  | double_converted_dt | dt_status | 
+-----------+----------------------+------------+ 
| 20019999 | 20090607    | Bad  | 
+-----------+----------------------+------------+