creare view 視圖名 AS
SQL語句
with read only --是否只讀
with check option --是否執(zhí)行約束檢查

-- 創(chuàng)建視圖

CREATE VIEW view_name AS SELECT * FROM dept WHERE deptno<20;

-- 修改視圖

CREATE OR REPLACE VIEW view_name AS SELECT * FROM dept WHERE deptno<20;

-- 去除視圖的相關(guān)約束
ALTER VIEW emp DROP CONSTRAINT ...

-- 查看所有視圖
SELECT * FROM user_views;

DROP VIEW 視圖名

-- 查看所有表

select * from table

--- 查看當(dāng)前用戶下的表

select * from tab

此處的tab就是一個同義詞

CREATE SYNONYM 同義詞名 FOR 視圖名；

--- 創(chuàng)建私有同義詞

create synonym syn_emp for emp;

--- 查看同義詞

select * from syn_emp;

--- 創(chuàng)建共有同義詞

create public synonym syn_dept for dept;

-- 用戶沒有訪問基表的權(quán)限，如果為基表創(chuàng)建了共有同義詞，那么依然看不到表信息

創(chuàng)建或替換現(xiàn)有同義詞

create or replace synonym emp_syn for scott.emp;

--- 刪除共有同義詞

drop public synonym syn_dept;

--- 刪除私有同義詞

drop synonym syn_dept;

SELECT * FROM 同義詞；