ClickHouse/docs/en/sql-reference/statements/alter/comment.md

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---
toc_priority: 51
toc_title: COMMENT
---
# ALTER TABLE … MODIFY COMMENT {#alter-modify-comment}
Adds, modifies, or removes comment to the table, regardless if it was set before or not. Comment change is reflected in both [system.tables](../../../operations/system-tables/tables.md) and `SHOW CREATE TABLE` query.
**Syntax**
``` sql
ALTER TABLE [db].name [ON CLUSTER cluster] MODIFY COMMENT 'Comment'
```
**Examples**
Creating a table with comment (for more information, see the [COMMENT] clause(../../../sql-reference/statements/create/table.md#comment-table)):
``` sql
CREATE TABLE table_with_comment
(
`k` UInt64,
`s` String
)
ENGINE = Memory()
COMMENT 'The temporary table';
```
Modifying the table comment:
``` sql
ALTER TABLE table_with_comment MODIFY COMMENT 'new comment on a table';
SELECT comment FROM system.tables WHERE database = currentDatabase() AND name = 'table_with_comment';
```
Output of a new comment:
```text
┌─comment────────────────┐
│ new comment on a table │
└────────────────────────┘
```
Removing the table comment:
``` sql
ALTER TABLE table_with_comment MODIFY COMMENT '';
SELECT comment FROM system.tables WHERE database = currentDatabase() AND name = 'table_with_comment';
```
Output of a removed comment:
```text
┌─comment─┐
│ │
└─────────┘
```