HIVE --，

HIVE --，

什么是视图？

  视图是一张“虚表”（只存在表的定义，不存储数据，表中逻辑上的数据来源于对其其它表的查询），如下图所示：

视图的作用

视图DDL

创建视图

  从创建语句可以看出，视图创建时就已经绑定了查询语句（即指明数据源和获取方式）；

CREATE VIEW [IF NOT EXISTS] [db_name.]view_name [(column_name [COMMENT column_comment], ...) ]
  [COMMENT view_comment]
  [TBLPROPERTIES (property_name = property_value, ...)]
  AS SELECT ...;

修改视图

• 修改绑定的查询语句

ALTER VIEW [db_name.]view_name AS select_statement;

• 修改视图属性

ALTER VIEW [db_name.]view_name SET TBLPROPERTIES table_properties;

删除视图

DROP VIEW [IF EXISTS] [db_name.]view_name;

视图DML

  视图只能查询，无法修改数据；

show语句

• 查看视图创建语句：SHOW CREATE VIEW [db_name.]view_name;
• 查看存在的视图：

SHOW VIEWS;                                -- show all views in the current database
SHOW VIEWS 'test_*';                       -- show all views that start with "test_"
SHOW VIEWS '*view2';                       -- show all views that end in "view2"
SHOW VIEWS LIKE 'test_view1|test_view2';   -- show views named either "test_view1" or "test_view2"
SHOW VIEWS FROM test1;                     -- show views from database test1
SHOW VIEWS IN test1;                       -- show views from database test1 (FROM and IN are same)
SHOW VIEWS IN test1 "test_*";              -- show views from database test2 that start with “test_"

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