51 lines
1.6 KiB
Markdown
51 lines
1.6 KiB
Markdown
---
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{
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"title": "ALTER VIEW",
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"language": "en"
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}
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---
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<!--
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Licensed to the Apache Software Foundation (ASF) under one
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or more contributor license agreements. See the NOTICE file
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distributed with this work for additional information
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regarding copyright ownership. The ASF licenses this file
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to you under the Apache License, Version 2.0 (the
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"License"); you may not use this file except in compliance
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with the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing,
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software distributed under the License is distributed on an
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"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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KIND, either express or implied. See the License for the
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specific language governing permissions and limitations
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under the License.
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-->
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# ALTER VIEW
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## description
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This statement is used to modify the definition of a view
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Syntax:
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ALTER VIEW
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[db_name.]view_name
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(column1[ COMMENT "col comment"][, column2, ...])
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AS query_stmt
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Explain:
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1. View is logical, it isn't stored in the physical medium. When we querying, view will be embed as subqueries in query statement. Therefore, modifying the definition of views is equivalent to modifying query_stmt which is defined in view.
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2. query_stmt is arbitrarily supported SQL.
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## example
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1. Modify example_view on the example_db
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ALTER VIEW example_db.example_view
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(
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c1 COMMENT "column 1",
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c2 COMMENT "column 2",
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c3 COMMENT "column 3"
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)
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AS SELECT k1, k2, SUM(v1) FROM example_table
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GROUP BY k1, k2 |