Data Science. SQL hub
По всем вопросам- @workakkk @itchannels_telegram - 🔥лучшие ит-каналы @ai_machinelearning_big_data - Machine learning @pythonl - Python @pythonlbooks- python книги📚 @datascienceiot - ml книги📚 РКН: https://vk.cc/cIi9vo #VRHSZ
Show more📈 Analytical overview of Telegram channel Data Science. SQL hub
Channel Data Science. SQL hub (@sqlhub) in the Russian language segment is an active participant. Currently, the community unites 35 982 subscribers, ranking 3 620 in the Technologies & Applications category and 17 762 in the Russia region.
📊 Audience metrics and dynamics
Since its creation on невідомо, the project has demonstrated rapid growth, gathering an audience of 35 982 subscribers.
According to the latest data from 02 September, 2026, the channel demonstrates stable activity. Although there has been a change in the number of participants by 107 over the last 30 days and by 8 over the last 24 hours, overall reach remains high.
- Verification status: Not verified
- Engagement rate (ER): The average audience engagement rate is 6.06%. Within the first 24 hours after publication, content typically collects 3.50% reactions from the total number of subscribers.
- Post reach: On average, each post receives 2 179 views. Within the first day, a publication typically gains 1 259 views.
- Reactions and interaction: The audience actively supports content: the average number of reactions per post is 9.
- Thematic interests: Content is focused on key topics such as sql, индекс, postgres, index, sqlite.
📝 Description and content policy
The author describes the resource as a platform for expressing subjective opinions:
“По всем вопросам- @workakkk
@itchannels_telegram - 🔥лучшие ит-каналы
@ai_machinelearning_big_data - Machine learning
@pythonl - Python
@pythonlbooks- python книги📚
@datascienceiot - ml книги📚
РКН: https://vk.cc/cIi9vo
#VRHSZ”
Thanks to the high frequency of updates (latest data received on 03 September, 2026), the channel maintains relevance and a high level of publication reach. Analytics show that the audience actively interacts with content, making it an important point of influence in the Technologies & Applications category.
-- Найдём последнюю покупку по каждому customer_id
SELECT o.*
FROM orders o
JOIN (
SELECT customer_id, MAX(order_date) AS max_date
FROM orders
GROUP BY customer_id
) latest
ON o.customer_id = latest.customer_id
AND o.order_date = latest.max_date;
-- Работает даже если в таблице десятки миллионов строк, индекс на order_date и customer_id ускорит запрос
@sqlhubGROUP BY и JOIN:
SELECT t1.*
FROM orders t1
JOIN (
SELECT customer_id, MIN(order_date) AS min_date
FROM orders
GROUP BY customer_id
) t2 ON t1.customer_id = t2.customer_id AND t1.order_date = t2.min_date;
✅ Этот приём вытаскивает первую покупку каждого клиента без оконных функций.
@sqlhubread_csv("flight_data.csv") → весь файл свалился в одну колонку
2. DuckDB SELECT * FROM read_csv('flight_data.csv') → автоматически подхватил разделитель и выдал аккуратные столбцы
💡 Вывод
Если работаете с CSV с нестандартным delimiter’ом, попробуйте прочитать его через DuckDB: детектирует разделители сам и экономит ваше время на ручной настройке.
@sqlhublevenshtein() из расширения pg_trgm в PostgreSQL, можно находить строки, отличающиеся ровно на 1 символ. Это удобно для очистки данных, поиска дублей и реализации "умного" поиска в интерфейсе.
-- Убедись, что pg_trgm расширение включено
CREATE EXTENSION IF NOT EXISTS pg_trgm;
-- Найдём строки из таблицы users, у которых name отличается на 1 символ
SELECT a.name AS name1, b.name AS name2
FROM users a
JOIN users b ON a.id < b.id
WHERE levenshtein(a.name, b.name) = 1;
-- Пример: найдёт пары вроде ('Anna', 'Anya') или ('John', 'Joan')
📌Больше видео
@sqlhub