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Document ALTER RENAME Column

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docs/en/sql-reference/statements/alter/column.md
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@ -24,6 +24,7 @@ The following actions are supported:
- [COMMENT COLUMN](#alter_comment-column) — Adds a text comment to the column.
- [MODIFY COLUMN](#alter_modify-column) — Changes column’s type, default expression and TTL.
- [MODIFY COLUMN REMOVE](#modify-remove) — Removes one of the column properties.
- [RENAME COLUMN](#alter_rename-column) — Renames an existing column.
These actions are described in detail below.
@ -166,6 +167,22 @@ ALTER TABLE table_with_ttl MODIFY COLUMN column_ttl REMOVE TTL;
- [REMOVE TTL](ttl.md).
## RENAME COLUMN {#alter_rename-column}
Renames an existing column.
Syntax:
```sql
ALTER TABLE table_name RENAME COLUMN column_name TO new_column_name;
```
**Example**
```sql
ALTER TABLE table_with_ttl RENAME COLUMN column_ttl TO column_ttl_new;
```
## Limitations {#alter-query-limitations}
The `ALTER` query lets you create and delete separate elements (columns) in nested data structures, but not whole nested data structures. To add a nested data structure, you can add columns with a name like `name.nested_name` and the type `Array(T)`. A nested data structure is equivalent to multiple array columns with a name that has the same prefix before the dot.