oracle不可更新的试图
关键词：with read only
作用：用于指定所创建的试图不可以通过本视图更新表
执行一下SQL，创建表T，和两个试图V1，V2：
CREATE TABLE T(ID INTEGER);
CREATE VIEW V1 AS SELECT * from T;
CREATE VIEW V2 AS SELECT * from T WITH READ ONLY;
执行SQL:
INSERT INTO V1 VALUES(1);
--------------------
1 row created
执行SQL:
INSERT INTO V2 VALUES(1);
--------------------
提示错误
单独的SELECT语句不能使用WITH READ ONLY
SELECT * from T WITH READ ONLY;
将不能运行。
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