mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-30 19:42:00 +00:00
23 lines
716 B
Markdown
23 lines
716 B
Markdown
|
---
|
||
|
|
toc_priority: 43
|
||
|
|
toc_title: CONSTRAINT
|
||
|
|
---
|
||
|
|
|
||
|
|
# Manipulating Constraints {#manipulations-with-constraints}
|
||
|
|
|
||
|
|
Constraints could be added or deleted using following syntax:
|
||
|
|
|
||
|
|
``` sql
|
||
|
|
ALTER TABLE [db].name ADD CONSTRAINT constraint_name CHECK expression;
|
||
|
|
ALTER TABLE [db].name DROP CONSTRAINT constraint_name;
|
||
|
|
```
|
||
|
|
|
||
|
|
See more on [constraints](../../../sql-reference/statements/create/table.md#constraints).
|
||
|
|
|
||
|
|
Queries will add or remove metadata about constraints from table so they are processed immediately.
|
||
|
|
|
||
|
|
!!! warning "Warning"
|
||
|
|
Constraint check **will not be executed** on existing data if it was added.
|
||
|
|
|
||
|
|
All changes on replicated tables are broadcasted to ZooKeeper and will be applied on other replicas as well.
|