1113f951c3
This commit adds a new statement named alter view, like ALTER VIEW view_name ( col_1, col_2, col_3, ) AS SELECT k1, k2, SUM(v1) FROM exampleDb.testTbl GROUP BY k1,k2
1.5 KiB
1.5 KiB
ALTER VIEW
description
This statement is used to modify the definition of a view
Syntax:
ALTER VIEW
[db_name.]view_name
(column1[ COMMENT "col comment"][, column2, ...])
AS query_stmt
Explain:
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.
2. query_stmt is arbitrarily supported SQL.
example
1. Modify example_view on the example_db
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