如何使用正则表达式将 hive 查询转换为 oracle

Question

I have this text:

Process explanation:The bottle is then melted to form liquid glass;Final activity for manager:Labeling of previous samples

I just want to get the part after 'Process explanation' but not include 'final activity...'

So like this:

The bottle is then melted to form liquid glass.

This is the current hive query which I want to convert to oracle:

SELECT REGEXP_EXTRACT(
               'Process explanation:The bottle is then melted to form liquid glass;Final activity for manager:Labeling of previous samples',
               '.*(process[ \t]*(explanation)?[ \t]*:[ \t]*)(.*?)([ \t]*;[ \t]*final[ \t]+activity[ \t]+for[ \t]+manager.*$|$)',
               3) as extracted
FROM my_table

Answer 1

If those substrings are just like you said, there's a pretty simple option - substr + instr functions.

SQL> with test (col) as
  2    (select 'Process explanation:The bottle is then melted to form liquid glass;Final activity for manager:Labeling of previous samples' from dual)
  3  select substr(col, instr(col, 'Process explanation') + length('Process explanation') + 1,
  4                     instr(col, 'Final activity') - instr(col, 'Process explanation') -
  5                       length('Process explanation') - 2
  6               ) result
  7  from test;

RESULT
----------------------------------------------
The bottle is then melted to form liquid glass

SQL>

Answer 2

I've come up with something like this:

with strings as
(SELECT '1Process explanation:The bottle is then melted to form liquid glass;Final activity for manager:Labeling of previous samples' str FROM DUAL
union all
SELECT '2Process explanation:The bottle is then melted to form liquid glass;' str FROM DUAL
union all
SELECT '3Process :The bottle is then melted to form liquid glass' str FROM DUAL
union all
SELECT '4Process explanation: plasma gasification combined with centrifugal activity' str FROM DUAL
union all
SELECT '5Final activity for manager:Labeling of previous samples' str FROM DUAL
)
SELECT str
, REGEXP_SUBSTR(
               str,
           '(.*process[[:blank:]]*(explanation)?[[:blank:]]*:[[:blank:]]*)([A-Za-z0-9 ]*)([[:blank:]]*;[[:blank:]]*final[[:blank:]]*activity[[:blank:]]*for[[:blank:]]*manager.*$)?',
           1, 1, 'i',3)
                as extracted
FROM strings

Resulting in:

STR	EXTRACTED
1Process explanation:The bottle is then melted to form liquid glass;Final activity for manager:Labeling of previous samples	The bottle is then melted to form liquid glass
2Process explanation:The bottle is then melted to form liquid glass;	The bottle is then melted to form liquid glass
3Process:The bottle is then melted to form liquid glass	The bottle is then melted to form liquid glass
4Process explanation: plasma gasification combined with centrifugal activity	plasma gasification combined with centrifugal activity
5Final activity for manager:Labeling of previous samples	-

Assuming matching blank group instead of your space and tab list [ \t] is ok. Edit: Modified the regexp a bit cause with possibility of last group being empty '.*' kept catching entire line.