ClickHouse/docs/zh/sql-reference/dictionaries/index.md

20 lines
846 B
Markdown
Raw Normal View History

---
2022-04-10 23:08:18 +00:00
sidebar_position: 35
sidebar_label: 字典
---
# 字典 {#dictionaries}
2021-05-23 14:12:43 +00:00
字典是一个映射 (`键 -> 属性`, 是方便各种类型的参考清单。
2021-05-23 14:12:43 +00:00
ClickHouse支持一些特殊函数配合字典在查询中使用。 将字典与函数结合使用比将 `JOIN` 操作与引用表结合使用更简单、更有效。
DOCS-624: Fixing links to nowhere (#10675) * enbaskakova-DOCSUP-652 (#101) * "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited" * "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited" * "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited" * Update docs/en/sql_reference/aggregate_functions/combinators.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/sql_reference/aggregate_functions/combinators.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/sql_reference/aggregate_functions/combinators.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/sql_reference/aggregate_functions/combinators.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/sql_reference/aggregate_functions/combinators.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited" * "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited" * "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited" Co-authored-by: elenbaskakova <elenbaskakova@yandex-team.ru> Co-authored-by: BayoNet <da-daos@yandex.ru> * Revert "enbaskakova-DOCSUP-652 (#101)" (#107) This reverts commit 639fee7610f28e421d14e535b7def3f466e7efca. * CLICKHOUSEDOCS-624: Fixed links. Was 60, became 13. * CLICKHOUSEDOCS-624: Finished fix links in Enlish version. * CLICKHOUSEDOCS-624: Fixed RU links Co-authored-by: elenaspb2019 <47083263+elenaspb2019@users.noreply.github.com> Co-authored-by: elenbaskakova <elenbaskakova@yandex-team.ru> Co-authored-by: Sergei Shtykov <bayonet@yandex-team.ru>
2020-05-06 06:13:29 +00:00
[NULL](../../sql-reference/syntax.md#null-literal) 值不能存储在字典中。
ClickHouse支持:
2021-05-23 14:12:43 +00:00
- [内置字典](internal-dicts.md#internal_dicts) ,这些字典具有特定的 [函数集](../../sql-reference/functions/ym-dict-functions.md).
- [插件(外部)字典](external-dictionaries/external-dicts.md#dicts-external-dicts) ,这些字典拥有一个 [函数集](../../sql-reference/functions/ext-dict-functions.md).
[原始文章](https://clickhouse.com/docs/en/query_language/dicts/) <!--hide-->