mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-09-24 18:50:49 +00:00
0a764bed54
* Create view.md Создал файл view.md и сделал описание функции view. * Update view.md I made changes. * Update view.md Changed parametrs. * Update view.md Changed by comments. * Create view.md Перевел на русский язык. * Update ru and en file view.md Changed by comments. * Update en and ru versions view function. Changed links. Co-authored-by: Dmitriy <sevirov@yandex-team.ru>
67 lines
1.7 KiB
Markdown
67 lines
1.7 KiB
Markdown
---
|
|
toc_priority: 51
|
|
toc_title: view
|
|
---
|
|
|
|
## view {#view}
|
|
|
|
Turns a subquery into a table. The function implements views (see [CREATE VIEW](https://clickhouse.tech/docs/en/sql-reference/statements/create/view/#create-view)). The resulting table doesn't store data, but only stores the specified `SELECT` query. When reading from the table, ClickHouse executes the query and deletes all unnecessary columns from the result.
|
|
|
|
**Syntax**
|
|
|
|
``` sql
|
|
view(subquery)
|
|
```
|
|
|
|
**Parameters**
|
|
|
|
- `subquery` — `SELECT` query.
|
|
|
|
**Returned value**
|
|
|
|
- A table.
|
|
|
|
**Example**
|
|
|
|
Input table:
|
|
|
|
``` text
|
|
┌─id─┬─name─────┬─days─┐
|
|
│ 1 │ January │ 31 │
|
|
│ 2 │ February │ 29 │
|
|
│ 3 │ March │ 31 │
|
|
│ 4 │ April │ 30 │
|
|
└────┴──────────┴──────┘
|
|
```
|
|
|
|
Query:
|
|
|
|
``` sql
|
|
SELECT * FROM view(SELECT name FROM months)
|
|
```
|
|
|
|
Result:
|
|
|
|
``` text
|
|
┌─name─────┐
|
|
│ January │
|
|
│ February │
|
|
│ March │
|
|
│ April │
|
|
└──────────┘
|
|
```
|
|
|
|
You can use the `view` function as a parameter of the [remote](https://clickhouse.tech/docs/en/sql-reference/table-functions/remote/#remote-remotesecure) and [cluster](https://clickhouse.tech/docs/en/sql-reference/table-functions/cluster/#cluster-clusterallreplicas) table functions:
|
|
|
|
``` sql
|
|
SELECT * FROM remote(`127.0.0.1`, view(SELECT a, b, c FROM table_name))
|
|
```
|
|
|
|
``` sql
|
|
SELECT * FROM cluster(`cluster_name`, view(SELECT a, b, c FROM table_name))
|
|
```
|
|
|
|
**See Also**
|
|
|
|
- [View Table Engine](https://clickhouse.tech/docs/en/engines/table-engines/special/view/)
|
|
[Original article](https://clickhouse.tech/docs/en/query_language/table_functions/view/) <!--hide--> |