mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-14 19:45:11 +00:00
6a8fa2d4a5
Implementation: * Added a new field allow_readonly to table system.table_functions. * Updated to use new field allow_readonly to allow using table functions in readonly mode. * Added TableFunctionProperties similar to AggregateFunctionProperties. * The functions allowed in readonly mode are in this set table_functions_allowed_in_readonly_mode. Testing: * Added a test for filesystem tests/queries/0_stateless/02473_functions_in_readonly_mode.sh Documentation: * Updated the english documentation for Table Functions.
45 lines
3.8 KiB
Markdown
45 lines
3.8 KiB
Markdown
---
|
||
slug: /en/sql-reference/table-functions/
|
||
sidebar_label: Table Functions
|
||
sidebar_position: 34
|
||
---
|
||
|
||
# Table Functions
|
||
|
||
Table functions are methods for constructing tables.
|
||
|
||
You can use table functions in:
|
||
|
||
- [FROM](../../sql-reference/statements/select/from.md) clause of the `SELECT` query.
|
||
|
||
The method for creating a temporary table that is available only in the current query. The table is deleted when the query finishes.
|
||
|
||
- [CREATE TABLE AS table_function()](../../sql-reference/statements/create/table.md) query.
|
||
|
||
It's one of the methods of creating a table.
|
||
|
||
- [INSERT INTO TABLE FUNCTION](../../sql-reference/statements/insert-into.md#inserting-into-table-function) query.
|
||
|
||
:::warning
|
||
You can’t use table functions if the [allow_ddl](../../operations/settings/permissions-for-queries.md#settings_allow_ddl) setting is disabled.
|
||
:::
|
||
|
||
| Function | Description |
|
||
|------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------|
|
||
| [file](../../sql-reference/table-functions/file.md) | Creates a [File](../../engines/table-engines/special/file.md)-engine table. |
|
||
| [merge](../../sql-reference/table-functions/merge.md) | Creates a [Merge](../../engines/table-engines/special/merge.md)-engine table. |
|
||
| [numbers](../../sql-reference/table-functions/numbers.md) | Creates a table with a single column filled with integer numbers. |
|
||
| [remote](../../sql-reference/table-functions/remote.md) | Allows you to access remote servers without creating a [Distributed](../../engines/table-engines/special/distributed.md)-engine table. |
|
||
| [url](../../sql-reference/table-functions/url.md) | Creates a [Url](../../engines/table-engines/special/url.md)-engine table. |
|
||
| [mysql](../../sql-reference/table-functions/mysql.md) | Creates a [MySQL](../../engines/table-engines/integrations/mysql.md)-engine table. |
|
||
| [postgresql](../../sql-reference/table-functions/postgresql.md) | Creates a [PostgreSQL](../../engines/table-engines/integrations/postgresql.md)-engine table. |
|
||
| [jdbc](../../sql-reference/table-functions/jdbc.md) | Creates a [JDBC](../../engines/table-engines/integrations/jdbc.md)-engine table. |
|
||
| [odbc](../../sql-reference/table-functions/odbc.md) | Creates a [ODBC](../../engines/table-engines/integrations/odbc.md)-engine table. |
|
||
| [hdfs](../../sql-reference/table-functions/hdfs.md) | Creates a [HDFS](../../engines/table-engines/integrations/hdfs.md)-engine table. |
|
||
| [s3](../../sql-reference/table-functions/s3.md) | Creates a [S3](../../engines/table-engines/integrations/s3.md)-engine table. |
|
||
| [sqlite](../../sql-reference/table-functions/sqlite.md) | Creates a [sqlite](../../engines/table-engines/integrations/sqlite.md)-engine table. |
|
||
|
||
:::note
|
||
Only these table functions are enabled in readonly mode :
|
||
null, view, viewIfPermitted, numbers, numbers_mt, generateRandom, values, cluster, clusterAllReplicas
|
||
::: |