语句如下：

create_view_stmt:
    CREATE [OR REPLACE] [MATERIALIZED] VIEW view_name
    [(column_name_list)] AS select_stmt;
drop_view_stmt:
    DROP VIEW [IF EXISTS] view_name_list;
view_name_list:
    view_name [, view_name ...]
column_name_list:
    column_name [, column_name ...]