mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-16 12:44:42 +00:00
67 lines
1.6 KiB
Markdown
67 lines
1.6 KiB
Markdown
---
|
|
slug: /en/sql-reference/table-functions/view
|
|
sidebar_position: 210
|
|
sidebar_label: view
|
|
title: view
|
|
---
|
|
|
|
Turns a subquery into a table. The function implements views (see [CREATE VIEW](https://clickhouse.com/docs/en/sql-reference/statements/create/view/#create-view)). The resulting table does not 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)
|
|
```
|
|
|
|
**Arguments**
|
|
|
|
- `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.com/docs/en/sql-reference/table-functions/remote/#remote-remotesecure) and [cluster](https://clickhouse.com/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.com/docs/en/engines/table-engines/special/view/)
|