---
{
    "title": "ALTER VIEW",
    "language": "zh-CN"
}
---

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# ALTER VIEW
## description
	该语句用于修改一个view的定义
	语法：
		ALTER VIEW
        [db_name.]view_name
        (column1[ COMMENT "col comment"][, column2, ...])
        AS query_stmt
        
    说明：
        1. 视图都是逻辑上的，其中的数据不会存储在物理介质上，在查询时视图将作为语句中的子查询，因此，修改视图的定义等价于修改query_stmt。
        2. query_stmt 为任意支持的 SQL
       
## example
	1、修改example_db上的视图example_view
	
		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