---
{
    "title": "ALTER-VIEW",
    "language": "en"
}
---

<!--
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.
-->

## ALTER-VIEW

### Name

ALTER VIEW

### Description

This statement is used to modify the definition of a view

grammar:

```sql
ALTER VIEW
[db_name.]view_name
(column1[ COMMENT "col comment"][, column2, ...])
AS query_stmt
```

illustrate:

- Views are all logical, and the data in them will not be stored on physical media. When querying, the view will be used as a subquery in the statement. Therefore, modifying the definition of the view is equivalent to modifying query_stmt.
- query_stmt is any supported SQL

### Example

1. Modify the view example_view on example_db

```sql
ALTER VIEW example_db.example_view
(
c1 COMMENT "column 1",
c2 COMMENT "column 2",
c3 COMMENT "column 3"
)
AS SELECT k1, k2, SUM(v1) FROM example_table
GROUP BY k1, k2
```

### Keywords

```text
ALTER, VIEW
```

### Best Practice