Regex_replace проверить только 1 экземпляр

Question

Привет, как создать регулярное выражение, которое шаблон должен иметь только 1 экземпляр "

Например:

1. STRING" 
2. "STRING
3. STRI"NG
4. STRING""
5. "STRING"

Результат:

1. STRING""
2. ""STRING
3. STRI""NG
4. STRING"" (No change since 2 instance of ")
5. "STRING"   (No change since 2 instance of ")

Answer 1

Примерно так:

with t as (
  select 'STRING"' as s from dual union all
  select '"STRING' from dual union all
  select 'STRI"NG' from dual union all
  select 'STRING""' from dual union all
  select '"STRING"' from dual union all
  select 'STRING' from dual union all
  select '"STR"ING"' from dual union all
  select '"' from dual union all
  select '""' from dual union all
  select '"""' from dual
)
select
  s,
  regexp_replace(s,'^([^"]*)"([^"]*)$', '\1""\2') new_s
from t

Вывод:

+-----------+-----------+
|     S     |   NEW_S   |
+-----------+-----------+
| STRING"   | STRING""  |
| "STRING   | ""STRING  |
| STRI"NG   | STRI""NG  |
| STRING""  | STRING""  |
| "STRING"  | "STRING"  |
| STRING    | STRING    |
| "STR"ING" | "STR"ING" |
| "         | ""        |
| ""        | ""        |
| """       | """       |
+-----------+-----------+

Объяснение:

^       # asserts position at start of a line
(       # 1st capturing group
 [^"]*  # matches characters that are not the character ", zero or more times
)
"       # matches the character " literally
(       # 2nd capturing group
 [^"]*
)
$       # asserts position at the end of a line

Проверьте это онлайн с rextester .