65 lines
1.9 KiB
Markdown
65 lines
1.9 KiB
Markdown
---
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{
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"title": "CREATE VIEW",
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"language": "zh-CN"
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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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# CREATE VIEW
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## description
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该语句用于创建一个逻辑视图
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语法：
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CREATE VIEW [IF NOT EXISTS]
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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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说明：
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1. 视图为逻辑视图，没有物理存储。所有在视图上的查询相当于在视图对应的子查询上进行。
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2. query_stmt 为任意支持的 SQL
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## example
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1. 在 example_db 上创建视图 example_view
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CREATE VIEW example_db.example_view (k1, k2, k3, v1)
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AS
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SELECT c1 as k1, k2, k3, SUM(v1) FROM example_table
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WHERE k1 = 20160112 GROUP BY k1,k2,k3;
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2. 创建一个包含 comment 的 view
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CREATE VIEW example_db.example_view
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(
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k1 COMMENT "first key",
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k2 COMMENT "second key",
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k3 COMMENT "third key",
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v1 COMMENT "first value"
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)
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COMMENT "my first view"
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AS
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SELECT c1 as k1, k2, k3, SUM(v1) FROM example_table
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WHERE k1 = 20160112 GROUP BY k1,k2,k3;
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## keyword
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CREATE,VIEW
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