Question

I am having an issue trying to convert multiple dates to one defined format. We are receiving the multiple dates from another DB source so I do not have control of the formatting until it reaches ours.

Here are all the formats:

YYYYMMDD

YYYY-MM-DD HH:MM:SS

MM/DD/YYYY

MM-DD-YYYY

Abrieviated Day Month DD HH:MM:SS TimeZone YYYY ('Thu Feb 02 20:49:59 MSK 2012')

Fully written Day, Month DD, YYYY HH:MM:SS AM/PM

My requirement is to set them all to the standard MM/DD/YYYY format or null. Any ideas?

Thank you.

Answer 1

我建议使用带有regexp_like条件的case语句来检测可能的格式并使用then子句中的相应日期掩码返回日期，例如：

with tz as (
SELECT distinct tzabbrev
     , first_value(min(tzname)) over (partition by tzabbrev order by count(*) desc) tzname
  FROM v$timezone_names 
 group by tzabbrev
     , TZ_OFFSET(tzname)
), dta as (
select yt.install_date
     , regexp_replace(yt.install_date,tzabbrev,tzname,1,1,'i') install_date2
  from your_table yt
  left join tz
    on regexp_like(install_date, tz.TZABBREV,'i')
)
select install_date, install_date2
     , to_timestamp_tz( install_date2
              , case 
                  when regexp_like(install_date2,'^[A-Z]{3,} [A-Z]{3,} [0-9]{1,2} [0-9]{1,2}(:[0-9]{2}){1,2} [[:print:]]{5,} [0-9]{2,4}','i') then 'DY MON DD HH24:MI:SS TZR YYYY'
                  when regexp_like(install_date2,'^[A-Z]{4,},? [A-Z]{3,},? [0-9]{1,2},? [0-9]{2,4}','i') then 'DAY MONTH DD YYYY'
                  when regexp_like(install_date2,'^[A-Z]{3},? [A-Z]{3,},? [0-9]{1,2},? [0-9]{2,4}','i') then 'DY MONTH DD YYYY'
                  when regexp_like(install_date2,'^[0-9]{1,2}[-/][0-9]{1,2}[-/]([0-9]{2}){1,2}') then 'MM-DD-RRRR'
                  when regexp_like(install_date2,'^[0-9]{1,2}[-/ ][A-Z]{3,}[-/ ]([0-9]{2}){1,2}','i') then 'DD-MON-RRRR'
                  when regexp_like(install_date2,'^[A-Z]{3,}[-/ ][0-9]{1,2},?[-/ ]([0-9]{2}){1,2}','i') then 'MON-DD-RRRR'
                  when regexp_like(install_date2,'^(19|20)[0-9]{6}') then 'RRRRMMDD'
                  when regexp_like(install_date2,'^[23][0-9]{5}') then 'DDMMRR'
                  when regexp_like(install_date2,'^[0-9]{6}') then 'MMDDRR'
                  when regexp_like(install_date2,'^[01][0-9]{7}') then 'MMDDRRRR'
                  when regexp_like(install_date2,'^[23][0-9]{7}') then 'DDMMRRRR'
                  ELSE NULL
                end
              ||case
                  when regexp_like(install_date2, '[0-9]{1,2}(:[0-9]{2}){1,2}$') then ' HH24:MI:SS'
                  when regexp_like(install_date2, '[0-9]{1,2}(:[0-9]{2}){1,2} ?(am|pm)$','i') then ' HH:MI:SS AM'
                  else null
                end
              )
              Install_Time_Stamp
  from dta;

我遇到时区缩写问题，所以我添加了一个步骤，首先用时区区域替换它们。

Answer 2

您可以定义转换函数，基本上按顺序处理每种格式：

create or replace function translate_date(i_date_string VARCHAR2) return date as
begin
-- you may optimize to not to go in all blocks based on the string format
-- order the blocks on the expected frequency
 begin
   return to_date(i_date_string,'yyyymmdd');
 EXCEPTION
   WHEN OTHERS  THEN NULL;
 end;  
 begin
   return to_date(i_date_string,'yyyy/mm/dd');
 EXCEPTION
   WHEN OTHERS  THEN NULL;
 end; 
 begin
   return to_date(i_date_string,'yyyy-mm-dd');
 EXCEPTION
   WHEN OTHERS  THEN NULL;
 end; 
 begin
   return to_date(i_date_string,'yyyy-mm-dd hh24:mi:ss');
 EXCEPTION
   WHEN OTHERS  THEN NULL;
 end; 
 begin
 -- transform to local timestamp and than to date
   return cast(cast(to_timestamp_tz(i_date_string,'dy month dd hh24:mi:ss tzr yyyy') as TIMESTAMP WITH LOCAL TIME ZONE) as date);
 EXCEPTION
   WHEN OTHERS  THEN NULL;
 end; 
 begin
   return to_date(i_date_string,'dy, month dd, yyyy hh:mi:ss am');
 EXCEPTION
   WHEN OTHERS  THEN NULL;
 end;  
 return NULL;
end;
/

例如样本数据

 TSTMP                                                                                              
 ------------------------
 20150101                                                                                             
 2015-01-01 23:59:59                                                                                  
 2015/01/01                                                                                           
 2015-01-01                                                                                           
 Thu Feb 02 20:49:59 Europe/Moscow 2012                                                               
 Thu, Feb 02, 2012 10:49:59 AM                                                                        
 Thu, Feb 02, 2012 10:49:59 PM

你得到了

TSTMP                                       RESULT_DATE       
------------------------------------------  -------------------
20150101                                    01.01.2015 00:00:00 
2015-01-01 23:59:59                         01.01.2015 23:59:59 
2015/01/01                                  01.01.2015 00:00:00 
2015-01-01                                  01.01.2015 00:00:00 
Thu Feb 02 20:49:59 Europe/Moscow 2012      02.02.2012 17:49:59 
Thu, Feb 02, 2012 10:49:59 AM               02.02.2012 10:49:59 
Thu, Feb 02, 2012 10:49:59 PM               02.02.2012 22:49:59

请注意，我跳过了时区abbraviation（MSK）的情况，请参阅@Sentinel答案中的可能解决方案，但请检查Conversion of String with Abbreviated Timezone to Timestamp这可能不明确。

Answer 3

由于to_date允许较小的偏差（不同的分隔符，缺少的分隔符，缺少的时间成分，2/4位数字的年份），因此可以稍微简化该功能。例如to_date(:str,'rrrr-mm-dd hh24:mi:ss')将覆盖

2020/09/18 01.02
2020.09.18 01
20200918010203
2020-0901
202009-01
20/09/18

To_timestamp_tz也可以容忍丢失的毫秒和时区（包括丢失的TZ元素TZM和TZD）。因此，我们基本上只需要注意主要变化，例如hh24 / hh，mm / mon，元素顺序，ISO 8601（2020-01-01T01：02：03）中的“ T”分隔符，TZ标记（UTC偏移{{1 }} /地区名称TZH:TZM）和星期几（DY）。

Convert multiple date varchar2 to date format in Oracle 11g

3 个答案: