Sure, here are some example codes demonstrating the usage of the main functions in Python's re module:

1. re.match(pattern, string, flags=0):
- This function attempts to match the pattern at the beginning of the string.

   import re
   result = re.match(r'Hello', 'Hello, World!')
   print(result.group(0))  # Output: Hello
   

2. re.search(pattern, string, flags=0):
- This function searches for the first occurrence of the pattern within the string.

   import re
   result = re.search(r'World', 'Hello, World!')
   print(result.group(0))  # Output: World
   

3. re.findall(pattern, string, flags=0):
- This function finds all occurrences of the pattern within the string and returns them as a list.

   import re
   results = re.findall(r'\d+', 'There are 123 apples and 456 oranges.')
   print(results)  # Output: ['123', '456']
   

4. re.finditer(pattern, string, flags=0):
- This function finds all occurrences of the pattern within the string and returns them as an iterator of match objects.

   import re
   matches = re.finditer(r'\d+', 'There are 123 apples and 456 oranges.')
   for match in matches:
       print(match.group(0))  # Output: 123, 456
   

5. re.sub(pattern, repl, string, count=0, flags=0):
- This function substitutes occurrences of the pattern in the string with the replacement string repl.

   import re
   result = re.sub(r'\d+', 'X', 'There are 123 apples and 456 oranges.')
   print(result)  # Output: There are X apples and X oranges.
   

6. re.split(pattern, string, maxsplit=0, flags=0):
- This function splits the string into substrings based on the occurrences of the pattern.

   import re
   parts = re.split(r'\s+', 'Split this string by spaces')
   print(parts)  # Output: ['Split', 'this', 'string', 'by', 'spaces']
   

These examples demonstrate how to use the main functions in Python's re module for pattern matching, searching, substitution, and splitting text based on regex patterns.

Regex

\d all numbers
\D not numbers
\W not number or letter
\ w only number or letter
\ s special characters
\ S not special characters

regex

recursive cte

lot timeframe news decs upper lower

WITH RECURSIVE EmployeeHierarchy AS (
SELECT
employee_id,
name,
manager_id,
1 AS depth
FROM employees
WHERE manager_id IS NULL -- начальная точка: верхний уровень иерархии
UNION ALL
SELECT
e.employee_id,
e.name,
e.manager_id,
eh.depth + 1
FROM employees e
INNER JOIN EmployeeHierarchy eh ON e.manager_id = eh.employee_id -- рекурсивное соединение
)
SELECT * FROM EmployeeHierarchy;

WITH RECURSIVE EmployeeHierarchy AS (
SELECT
employee_id,
name,
manager_id,
1 AS depth
FROM employees
WHERE employees.name = 'Senior Otabek' -- начальная точка: верхний уровень иерархии
UNION ALL
SELECT
e.employee_id,
e.name,
e.manager_id,
eh.depth + 1
FROM employees e
INNER JOIN EmployeeHierarchy eh ON e.manager_id = eh.employee_id -- рекурсивное соединение
)

%S means ends with
S% means starts with

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