ClickHouse/docs/ru/query_language/operators.md

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# Операторы
Все операторы преобразуются в соответствующие функции на этапе парсинга запроса, с учётом их приоритетов и ассоциативности.
Далее будут перечислены группы операторов в порядке их приоритета (чем выше, тем раньше оператор связывается со своими аргументами).
## Операторы доступа
`a[N]` - доступ к элементу массива, функция `arrayElement(a, N)`.
`a.N` - доступ к элементу кортежа, функция `tupleElement(a, N)`.
## Оператор числового отрицания
`-a` - функция `negate(a)`.
## Операторы умножения и деления
`a * b` - функция `multiply(a, b)`
`a / b` - функция `divide(a, b)`
`a % b` - функция `modulo(a, b)`
## Операторы сложения и вычитания
`a + b` - функция `plus(a, b)`
`a - b` - функция `minus(a, b)`
## Операторы сравнения
`a = b` - функция `equals(a, b)`
`a == b` - функция `equals(a, b)`
`a != b` - функция `notEquals(a, b)`
`a <> b` - функция `notEquals(a, b)`
`a <= b` - функция `lessOrEquals(a, b)`
`a >= b` - функция `greaterOrEquals(a, b)`
`a < b` - функция `less(a, b)`
`a > b` - функция `greater(a, b)`
`a LIKE s` - функция `like(a, b)`
`a NOT LIKE s` - функция `notLike(a, b)`
`a BETWEEN b AND c` - равнозначно `a >= b AND a <= c`
## Операторы для работы с множествами
*Смотрите раздел [Операторы IN](select.md#select-in-operators).*
`a IN ...` - функция `in(a, b)`
`a NOT IN ...` - функция `notIn(a, b)`
`a GLOBAL IN ...` - функция `globalIn(a, b)`
`a GLOBAL NOT IN ...` - функция `globalNotIn(a, b)`
## Оператор логического отрицания
`NOT a` - функция `not(a)`
## Оператор логического 'И'
`a AND b` - функция `and(a, b)`
## Оператор логического 'ИЛИ'
`a OR b` - функция `or(a, b)`
## Условный оператор
`a ? b : c` - функция `if(a, b, c)`
Примечание:
Условный оператор сначала вычисляет значения b и c, затем проверяет выполнение условия a, и только после этого возвращает соответствующее значение. Если в качестве b или с выступает функция [arrayJoin()](functions/array_join.md#functions_arrayjoin), то размножение каждой строки произойдет вне зависимости от условия а.
## Условное выражение {#operator_case}
``` sql
CASE [x]
WHEN a THEN b
[WHEN ... THEN ...]
[ELSE c]
END
```
В случае указания `x` - функция `transform(x, [a, ...], [b, ...], c)`. Иначе — `multiIf(a, b, ..., c)`.
При отсутствии секции `ELSE c`, значением по умолчанию будет `NULL`.
P.S. Функция `transform` не умеет работать с `NULL`.
## Оператор склеивания строк
`s1 || s2` - функция `concat(s1, s2)`
## Оператор создания лямбда-выражения
`x -> expr` - функция `lambda(x, expr)`
Следующие операторы не имеют приоритета, так как представляют собой скобки:
## Оператор создания массива
`[x1, ...]` - функция `array(x1, ...)`
## Оператор создания кортежа
`(x1, x2, ...)` - функция `tuple(x2, x2, ...)`
## Ассоциативность
Все бинарные операторы имеют левую ассоциативность. Например, `1 + 2 + 3` преобразуется в `plus(plus(1, 2), 3)`.
Иногда это работает не так, как ожидается. Например, `SELECT 4 > 3 > 2` выдаст 0.
Для эффективности, реализованы функции `and` и `or`, принимающие произвольное количество аргументов. Соответствующие цепочки операторов `AND` и `OR`, преобразуются в один вызов этих функций.
## Проверка на `NULL`
ClickHouse поддерживает операторы `IS NULL` и `IS NOT NULL`.
### IS NULL {#operator-is-null}
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 * get rid of tabs @ custom.css * Apply comments and patch from #3384 * Add jdbc.md to ToC and some translation, though it still looks badly incomplete * minor punctuation * Add some backlinks to official website from mirrors that just blindly take markdown sources * Do not make fonts extra light * 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 * Not so light font on front page too * Refactor Chinese formats.md to match recent changes in other languages * Update some links on front page * Remove some outdated comment * Add twitter link to front page * More front page links tuning * Add Amsterdam meetup link * Smaller font to avoid second line * Add Amsterdam link to README.md * Proper docs nav translation * Back to 300 font-weight except Chinese * fix docs build * Update Amsterdam link * remove symlinks * more zh punctuation * apply lost comment by @zhang2014 * Apply comments by @zhang2014 from #3417 * Remove Beijing link * rm incorrect symlink * restore content of docs/zh/operations/table_engines/index.md * CLICKHOUSE-3751: stem terms while searching docs * CLICKHOUSE-3751: use English stemmer in non-English docs too * CLICKHOUSE-4135 fix * Remove past meetup link * Add blog link to top nav * Add ContentSquare article link * Add form link to front page + refactor some texts * couple markup fixes * minor * Introduce basic ODBC driver page in docs * More verbose 3rd party libs disclaimer * Put third-party stuff into a separate folder * 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 * http_interface.md -> http.md * fix link * Remove unconvenient error for now * try to guess anchor instead of failing * remove symlink * Remove outdated info from introduction * remove ru roadmap.md * replace ru roadmap.md with symlink * Update roadmap.md * lost file * Title case in toc_en.yml * Sync "Functions" ToC section with en * Remove reference to pretty old ClickHouse release from docs * couple lost symlinks in fa * Close quote in proper place * Rewrite en/getting_started/index.md * Sync en<>ru getting_started/index.md * minor changes * Some gui.md refactoring * Translate DataGrip section to ru * Translate DataGrip section to zh * Translate DataGrip section to fa * Translate DBeaver section to fa * 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 * Lost blank lines * Fix class name * More rel="external nofollow" * Apply suggestions by @sundy-li * Mobile version of front page improvements * test * test 2 * test 3 * Update LICENSE * minor docs fix * Highlight current article as suggested by @sundy-li * fix link destination * 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 * Add clickhouse-bulk to proxy.md * Major extension of integrations.md contents * fix link target * remove unneeded file * better toc item name * fix markdown * better ru punctuation * Add yet another possible backup approach * Simplify copying permalinks to headers * Support non-eng link anchors in docs + update some deps * Generate anchors for single-page mode automatically * Remove anchors to top of pages * Remove anchors that nobody links to * build fixes * fix few links * restore css * fix some links * restore gifs * fix lost words * more docs fixes * docs fixes * NULL anchor * update urllib3 dependency * more fixes
2018-12-12 17:28:00 +00:00
- Для значений типа [Nullable](../data_types/nullable.md) оператор `IS NULL` возвращает:
- `1`, если значение — `NULL`.
- `0` в обратном случае.
- Для прочих значений оператор `IS NULL` всегда возвращает `0`.
```bash
:) SELECT x+100 FROM t_null WHERE y IS NULL
SELECT x + 100
FROM t_null
WHERE isNull(y)
┌─plus(x, 100)─┐
│ 101 │
└──────────────┘
1 rows in set. Elapsed: 0.002 sec.
```
2018-07-17 05:48:14 +00:00
### IS NOT NULL
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 * get rid of tabs @ custom.css * Apply comments and patch from #3384 * Add jdbc.md to ToC and some translation, though it still looks badly incomplete * minor punctuation * Add some backlinks to official website from mirrors that just blindly take markdown sources * Do not make fonts extra light * 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 * Not so light font on front page too * Refactor Chinese formats.md to match recent changes in other languages * Update some links on front page * Remove some outdated comment * Add twitter link to front page * More front page links tuning * Add Amsterdam meetup link * Smaller font to avoid second line * Add Amsterdam link to README.md * Proper docs nav translation * Back to 300 font-weight except Chinese * fix docs build * Update Amsterdam link * remove symlinks * more zh punctuation * apply lost comment by @zhang2014 * Apply comments by @zhang2014 from #3417 * Remove Beijing link * rm incorrect symlink * restore content of docs/zh/operations/table_engines/index.md * CLICKHOUSE-3751: stem terms while searching docs * CLICKHOUSE-3751: use English stemmer in non-English docs too * CLICKHOUSE-4135 fix * Remove past meetup link * Add blog link to top nav * Add ContentSquare article link * Add form link to front page + refactor some texts * couple markup fixes * minor * Introduce basic ODBC driver page in docs * More verbose 3rd party libs disclaimer * Put third-party stuff into a separate folder * 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 * http_interface.md -> http.md * fix link * Remove unconvenient error for now * try to guess anchor instead of failing * remove symlink * Remove outdated info from introduction * remove ru roadmap.md * replace ru roadmap.md with symlink * Update roadmap.md * lost file * Title case in toc_en.yml * Sync "Functions" ToC section with en * Remove reference to pretty old ClickHouse release from docs * couple lost symlinks in fa * Close quote in proper place * Rewrite en/getting_started/index.md * Sync en<>ru getting_started/index.md * minor changes * Some gui.md refactoring * Translate DataGrip section to ru * Translate DataGrip section to zh * Translate DataGrip section to fa * Translate DBeaver section to fa * 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 * Lost blank lines * Fix class name * More rel="external nofollow" * Apply suggestions by @sundy-li * Mobile version of front page improvements * test * test 2 * test 3 * Update LICENSE * minor docs fix * Highlight current article as suggested by @sundy-li * fix link destination * 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 * Add clickhouse-bulk to proxy.md * Major extension of integrations.md contents * fix link target * remove unneeded file * better toc item name * fix markdown * better ru punctuation * Add yet another possible backup approach * Simplify copying permalinks to headers * Support non-eng link anchors in docs + update some deps * Generate anchors for single-page mode automatically * Remove anchors to top of pages * Remove anchors that nobody links to * build fixes * fix few links * restore css * fix some links * restore gifs * fix lost words * more docs fixes * docs fixes * NULL anchor * update urllib3 dependency * more fixes
2018-12-12 17:28:00 +00:00
- Для значений типа [Nullable](../data_types/nullable.md) оператор `IS NOT NULL` возвращает:
- `0`, если значение — `NULL`.
- `1`, в обратном случае.
- Для прочих значений оператор `IS NOT NULL` всегда возвращает `1`.
```bash
:) SELECT * FROM t_null WHERE y IS NOT NULL
SELECT *
FROM t_null
WHERE isNotNull(y)
┌─x─┬─y─┐
│ 2 │ 3 │
└───┴───┘
1 rows in set. Elapsed: 0.002 sec.
```
[Оригинальная статья](https://clickhouse.yandex/docs/ru/query_language/operators/) <!--hide-->