SQL задачи для подготовки к собеседованию.
SQL тесты для проверки знаний.
№ 7065181110
SQL запросы к конкретной Базе данных с решением и разбором
По вопросам рекламы: @anothertechrock
Created
Between 1 April 2018 and 31 July 2021 — estimated from Telegram’s id allocation, not measured. How this range is calculated.
Education — a classification, not a measurement. An on-box language model (Qwen3.6-35B-A3B-FP8, prompt version 1) read this channel’s own recent posts on 11 September 2026 and assigned it the closest of 31 fixed categories, at 96% confidence. This is a model’s judgement about what the channel is likely to be about, not a fact this register measured the way a subscriber count or a view count is measured — it can be revised on a later pass, and it carries no weight anywhere else on this page. How this classification works, and the other topics.
Growth
42 measurements spanning 94 days, net -85. Dots are measurements; the straight line between them is drawn to join them, not to claim we know the path taken in between — snapshots are recorded only when a count changes, so gaps mean “no change observed”, never “interpolated”. The vertical axis spans 9,929–10,040 and does not start at zero.
Measurement log — every subscribers count we have recorded, most recent 20 of 42
Measured (UTC)
Subscribers
Change
8 Nov 2026, 04:00
9,942
-5
4 Nov 2026, 21:27
9,947
-4
30 Oct 2026, 15:09
9,951
-11
27 Oct 2026, 05:26
9,962
-3
24 Oct 2026, 07:48
9,965
-8
21 Oct 2026, 08:09
9,973
-3
18 Oct 2026, 16:17
9,976
+2
15 Oct 2026, 12:30
9,974
+1
12 Oct 2026, 06:39
9,973
-4
5 Oct 2026, 06:16
9,977
-12
26 Sept 2026, 12:59
9,989
-1
15 Sept 2026, 11:38
9,990
-7
12 Sept 2026, 00:01
9,997
-5
9 Sept 2026, 16:41
10,002
+1
6 Sept 2026, 11:40
10,001
-2
4 Sept 2026, 04:39
10,003
-4
2 Sept 2026, 17:53
10,007
+1
1 Sept 2026, 17:08
10,006
-1
30 Aug 2026, 21:18
10,007
+2
29 Aug 2026, 23:47
10,005
first reading
Engagement
25 posts held, back to 22 April 2026 — the reader has not yet reached the start of this channel’s public history, so older posts may sit further back, unread. Read across 53 pages of Telegram’s post history, 20 posts per page.
Nothing published in the last 30 days. ERR and ER are rolling 30-day measures, so there is nothing to compute — we hold 25 posts for this entry, the most recent from 7 October 2026. An engagement rate over an empty window would be a number about nothing.
What this channel posts
Photos
191
Links
136
Lifetime counters from Telegram’s own channel header, read 10 November 2026 — not the date at the top of this page, which is when the subscriber count was last read. Below Telegram’s rounding threshold, so these counts are exact.
Reaction mix
70 reactions across 15 posts, in 8 distinct kinds. The most used accounts for 47.1% of them.
Every reaction kind recorded on the sample, most used first
Reaction
Count
Share
Share, drawn
🔥
33
47.1%
👍
21
30.0%
😁
5
7.14%
😱
3
4.29%
🙏
3
4.29%
🤮
2
2.86%
🥰
2
2.86%
🤔
1
1.43%
No sentiment is inferred, and none should be read in. This table is ordered by count and by nothing else. Emoji do not carry stable meaning across languages or communities — 🙏 is thanks in one channel and mourning in another — so we publish which ones were pressed and how often, and pass no judgement on what an audience meant by them.
Precision. Telegram publishes reaction counts per emoji and short-forms each one — 4.34K, 1.2M — so any single kind at or above 1,000 reaches us at three significant figures, and only counts below 1,000 are exact. The shares above are ratios of those figures and carry the same error. This is also why the total here can differ slightly from a reaction total printed elsewhere on the page: both are sums of the same rounded parts, taken over samples with different edges.
Coverage. Reactions were read on 15 of the 25 sampled posts in this sample. Summed by Telegram’s own count on each post — not by adding up the per-emoji breakdown above — those same posts carry 70 reactions in total: the kind of figure the paragraph above means by “a reaction total printed elsewhere on the page”.
Measured over the 25 most recent posts we hold, published 22 April 2026 to 7 October 2026, using the newest reading held for each. Telegram Stars are excluded: they are a payment, not a reaction, and they have their own section.
Задачка по нашей базе данных, которую можно найти в шапке канала.
Код генерации базы данных и INSERT данных по ссылке ТУТ.
ВОПРОС: Какой JOIN нужно использовать, чтобы получить только тех клиентов, которые сделали заказы?
SELECT c.first_name, c.last_name, o.order_id FROM customer c
[INNER/LEFT/CROSS/ FULL] JOIN order_table o ON c.customer_id = o.customer_id;
Ответ под спойлером, но если хотите сперва проверить св…
Задачка по нашей базе данных, которая находится в шапке канала.
Код генерации базы данных и INSERT данных по ссылке ТУТ.
ВОПРОС: Какой запрос позволяет проверить, есть ли дубликаты product_id в таблице product?
Ответ под спойлером, но если хотите сперва проверить свою догадку, следующим постом опубликуем тест с вариантами ответов.
SELECT COUNT(DISTINCT product_id), COUNT(product_id) FROM product;
Если вам понрави…
Что вернёт запрос?
SELECT SUBSTRING(email, 1, LOCATE('@', email) - 1) FROM customer WHERE customer_id = 1;
Схема БД и код для генерации данных находятся в шапке канала.
Запрос не выдает число или конкретную категорию. Просто опишите результат своими словами в комментариях. А для тех, кто предпочитает тесты, опубликуем тест с вариантами ответа в следующем посте.
Если вам понравился вопрос - зашарьте его друзьям 👉 …
Список гендеров, в группах которых менее 5 клиентов75%
Список всех клиентов с указанием их пола1%
Ошибку, так как HAVING COUNT(*) недопустим12%
Список гендеров, в группах которых 5 и более клиентов12%
Shares as published. No per-option vote count is published by Telegram, so none is shown.
Showing the 12 most recent of 25 posts we hold for @sqlquestions. View and reaction counts are the latest single reading for each post, not a live figure, and a recent post is still accumulating both. A view count marked ≈ was rounded by Telegram before we ever saw it — t.me prints views in full below 1,000 and to three significant figures above, so ≈1,200,000 means somewhere between 1,150,000 and 1,249,999. Unmarked counts are exact. Text is reproduced from the public post preview and truncated for length.
Posts recorded as deleted after publishing
We recorded 1 post on @sqlquestions as deleted — posts this register held that were missing from the channel’s public page on two separate reads, taken from different network addresses at least an hour apart.
A deletion is not wrongdoing. This register can see that a post it held is no longer on the channel’s public page, and when — not why. Expired ad placements, reposts, rotating links and corrections all look the same. This is a count of recorded detections, not an exact total: it misses deletions we could not see, because only a post we held and later re-read inside the page can be seen to go, and it may include a small number of wrong records. How this is measured.
First seen missing
3 November 2026
Most recent seen missing
3 November 2026
Median time before seen missing
3 months
Seen missing in the last 30 days
1
Polls
The 6 most recent of 11 polls we hold for this entry, as Telegram rendered them when we read the post. A poll’s figures keep moving after that, so each one is dated.
Для наделения суперпользователя правами администратора19%
Для выбора пользователей с последующим наделением их набором определенных прав38%
Такого оператора не существует43%
Shares as published. No per-option vote count is published by Telegram, so none is shown.
Percentages only — there are no per-option vote counts here, because Telegram publishes none. The public post preview gives each option’s share and a single voter total, and nothing else. Multiplying one by the other would produce a per-option tally that looks measured and is not: the shares are rounded to whole numbers before we ever see them. We print what was published and leave the column that does not exist empty.
The shares need not add up to 100. Rounding alone puts many polls at 99 or 101. A poll that allows more than one answer per voter runs well past 100 by design, and several here do. The bars are drawn against a fixed 100% track at each option’s own percentage rather than normalised to the total, so a poll that exceeds it shows that it does instead of being quietly rescaled.
Read from the 25 most recent posts we hold, published 22 April 2026 to 7 October 2026. Telegram labels each poll by kind — an anonymous poll, a quiz, a closed set of final results — and that label is reproduced rather than paraphrased.
Appears in Telegram’s recommendations for other channels
The reverse of the list above, and a different kind of signal. This does not require this channel to have ever been asked about directly — each row below is a channel we DID ask Telegram about, whose Telegram-generated list happened to include this one. A channel can appear here with an empty list above it, because being named by someone else’s query is independent of having been queried itself.
Pythonist.ru - образование по питону @pythonist_ru · 23,873 Telegram ranks this channel #26 of 82 here — alongside 81 others — read 17 September 2026
Базы данных | Access, SQL, Big Data @databases_secrets · 30,012 Telegram ranks this channel #29 of 82 here — alongside 81 others — read 7 September 2026
Секреты аналитики | Data Science, BI, Tableau @analytics_secrets · 46,814 Telegram ranks this channel #45 of 85 here — alongside 84 others — read 27 August 2026
This channel appears in 3 seed channels' Telegram-generated recommendation lists in total. Each is Telegram’s list for THAT channel, not this one — see how this is measured.
Cite this entry
A live page changes as we take new readings, so a citation should name the measurement it is based on, not just the URL. The line below cites the subscriber count as measured 8 November 2026 — this
entry's latest reading, not the date you are reading this.
“SQL задачи” (@sqlquestions), 9,942 subscribers as measured 8 November 2026. Telegram Register, tgregister.com/channel/sqlquestions.
Full measurement history, CC BY 4.0. Every reading this register holds for this entry, not just the latest one, as a dated, downloadable record: CSV · JSON. Free to use with attribution to tgregister.com. Each file carries its own generation timestamp, which is the figure to cite for exactly when the data was retrieved.