# Modify Table Structure

Use the ALTER statement to modify the structure of a table.

**Basic Syntax:**

```
# Column operations on the table
ALTER TABLE [db].name [ON CLUSTER cluster] ADD COLUMN [IF NOT EXISTS] name [type] [default_expr] [codec] [AFTER name_after]ALTER TABLE [db].name [ON CLUSTER cluster] DROP COLUMN [IF EXISTS] nameALTER TABLE [db].name [ON CLUSTER cluster] CLEAR COLUMN [IF EXISTS] name IN PARTITION partition_nameALTER TABLE [db].name [ON CLUSTER cluster] COMMENT COLUMN [IF EXISTS] name 'comment'ALTER TABLE [db].name [ON CLUSTER cluster] MODIFY COLUMN [IF EXISTS] name [type] [default_expr] [TTL]

# Partition operations on the table
ALTER TABLE table_name DETACH PARTITION partition_exprALTER TABLE table_name DROP PARTITION partition_exprALTER TABLE table_name CLEAR INDEX index_name IN PARTITION partition_expr

# Table attributes operations
ALTER TABLE table-name MODIFY TTL ttl-expression
```

For more information, please refer to the [official documentation](https://clickhouse.com/docs/en/sql-reference/statements/alter/).