mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-08 16:42:04 +00:00
2aefe5fb77
* Docs in English. * Fixed links bug. * Update docs/en/sql-reference/statements/alter/delete.md Co-authored-by: Ivan Blinkov <github@blinkov.ru> * Translated into Russian. Anchors in links syncronized with English text. One minor change in English text to unify two similar descriptions. Co-authored-by: Olga Revyakina <revolg@yandex-team.ru> Co-authored-by: Ivan Blinkov <github@blinkov.ru>
29 lines
1.5 KiB
Markdown
29 lines
1.5 KiB
Markdown
---
|
|
toc_priority: 40
|
|
toc_title: UPDATE
|
|
---
|
|
|
|
# ALTER TABLE … UPDATE Statements {#alter-table-update-statements}
|
|
|
|
``` sql
|
|
ALTER TABLE [db.]table UPDATE column1 = expr1 [, ...] WHERE filter_expr
|
|
```
|
|
|
|
Allows to manipulate data matching the specified filtering expression. Implemented as a [mutation](../../../sql-reference/statements/alter/index.md#mutations).
|
|
|
|
!!! note "Note"
|
|
The `ALTER TABLE` prefix makes this syntax different from most other systems supporting SQL. It is intended to signify that unlike similar queries in OLTP databases this is a heavy operation not designed for frequent use.
|
|
|
|
The `filter_expr` must be of type `UInt8`. This query updates values of specified columns to the values of corresponding expressions in rows for which the `filter_expr` takes a non-zero value. Values are casted to the column type using the `CAST` operator. Updating columns that are used in the calculation of the primary or the partition key is not supported.
|
|
|
|
One query can contain several commands separated by commas.
|
|
|
|
The synchronicity of the query processing is defined by the [mutations_sync](../../../operations/settings/settings.md#mutations_sync) setting. By default, it is asynchronous.
|
|
|
|
**See also**
|
|
|
|
- [Mutations](../../../sql-reference/statements/alter/index.md#mutations)
|
|
- [Synchronicity of ALTER Queries](../../../sql-reference/statements/alter/index.md#synchronicity-of-alter-queries)
|
|
- [mutations_sync](../../../operations/settings/settings.md#mutations_sync) setting
|
|
|