ClickHouse/docs/ru/operations/table_engines/mysql.md
Ivan Blinkov 16ca492938
WIP on docs (#3813)
* CLICKHOUSE-4063: less manual html @ index.md

* CLICKHOUSE-4063: recommend markdown="1" in README.md

* CLICKHOUSE-4003: manually purge custom.css for now

* CLICKHOUSE-4064: expand <details> before any print (including to pdf)

* CLICKHOUSE-3927: rearrange interfaces/formats.md a bit

* CLICKHOUSE-3306: add few http headers

* Remove copy-paste introduced in #3392

* Hopefully better chinese fonts #3392

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* Add jdbc.md to ToC and some translation, though it still looks badly incomplete

* minor punctuation

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* find . -name '*.md' -type f | xargs -I{} perl -pi -e 's//g' {}

* find . -name '*.md' -type f | xargs -I{} perl -pi -e 's/ sql/g' {}

* Remove outdated stuff from roadmap.md

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* fix docs build

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* CLICKHOUSE-3751: stem terms while searching docs

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* More verbose 3rd party libs disclaimer

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* Separate third-party stuff in ToC too

* Update links

* Move stuff that is not really (only) a client library into a separate page

* Add clickhouse-hdfs-loader link

* Some introduction for "interfaces" section

* Rewrite tcp.md

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* fix link

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* minor changes

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* Translate DataGrip section to zh

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* Translate DBeaver section to zh

* Split third-party GUI to open-source and commercial

* Mention some RDBMS integrations + ad-hoc translation fixes

* Add rel="external nofollow" to outgoing links from docs

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* More rel="external nofollow"

* Apply suggestions by @sundy-li

* Mobile version of front page improvements

* test

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* Update LICENSE

* minor docs fix

* Highlight current article as suggested by @sundy-li

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* Introduce backup.md (only "en" for now)

* Mention INSERT+SELECT in backup.md

* Some improvements for replication.md

* Add backup.md to toc

* Mention clickhouse-backup tool

* Mention LightHouse in third-party GUI list

* Introduce interfaces/third-party/proxy.md

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* Support non-eng link anchors in docs + update some deps

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* Remove anchors to top of pages

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* build fixes

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* docs fixes

* NULL anchor

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2018-12-12 20:28:00 +03:00

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# MySQL
Движок MySQL позволяет выполнять `SELECT` запросы над данными, хранящимися на удалённом MySQL сервере.
Формат вызова:
```
MySQL('host:port', 'database', 'table', 'user', 'password'[, replace_query, 'on_duplicate_clause']);
```
**Параметры вызова**
- `host:port` — Адрес сервера MySQL.
- `database` — Имя базы данных на сервере MySQL.
- `table` — Имя таблицы.
- `user` — Пользователь MySQL.
- `password` — Пароль пользователя.
- `replace_query` — Флаг, устанавливающий замену запроса `INSERT INTO` на `REPLACE INTO`. Если `replace_query=1`, то запрос заменяется.
- `on_duplicate_clause` — Добавляет выражение `ON DUPLICATE KEY 'on_duplicate_clause'` в запрос `INSERT`.
Например, `INSERT INTO t (c1,c2) VALUES ('a', 2) ON DUPLICATE KEY UPDATE c2 = c2 + 1`, где `on_duplicate_clause``UPDATE c2 = c2 + 1`. Какие выражения `on_duplicate_clause` вы можете использовать с `ON DUPLICATE KEY`, смотрите в документации MySQL.
Чтобы указать `on_duplicate_clause` необходимо передать `0` в параметр `replace_query`. Если одновременно передать `replace_query = 1` и `on_duplicate_clause`, то ClickHouse сгенерирует исключение.
На данный момент простые условия `WHERE`, такие как `=, !=, >, >=, <, <=` будут выполняться на стороне сервера MySQL.
Остальные условия и ограничение выборки `LIMIT` будут выполнены в ClickHouse только после выполнения запроса к MySQL.
Движок `MySQL` не поддерживает тип данных [Nullable](../../data_types/nullable.md), поэтому при чтении данных из таблиц MySQL `NULL` преобразуются в значения по умолчанию для заданного типа столбца, обычно это 0 или пустая строка.
[Оригинальная статья](https://clickhouse.yandex/docs/ru/operations/table_engines/mysql/) <!--hide-->