Question

我有一个错字的观点：

CREATE OR REPLACE VIEW "USER"."VW_X" AS (
SELECT id, 
       name, 
       decode(WRONG_COLUMN, 1, 'T', 0, 'F') AS problem
FROM "USER"."TEST");

出于某种原因使用

CREATE OR REPLACE VIEW "USER"."VW_X" AS (
SELECT id, 
       name, 
       decode(RIGHT_COLUMN, 1, 'T', 0, 'F') AS problem
FROM "USER"."TEST");

会产生以下消息：

Error starting at line : 5 in command -
CREATE OR REPLACE VIEW "USER"."VW_X" AS (
SELECT id, 
       name, 
       decode(RIGHT_COLUMN, 1, 'T', 0, 'F') AS problem
FROM "USER"."TEST")
Error report -
SQL Error: ORA-02449: unique/primary keys in table referenced by foreign keys
02449. 00000 -  "unique/primary keys in table referenced by foreign keys"
*Cause:    An attempt was made to drop a table with unique or
           primary keys referenced by foreign keys in another table.
*Action:   Before performing the above operations the table, drop the
           foreign key constraints in other tables. You can see what
           constraints are referencing a table by issuing the following
           command:
           SELECT * FROM USER_CONSTRAINTS WHERE TABLE_NAME = "tabnam";

我甚至不知道视图是参考的有效目标。所以这就是问题所在：

SELECT * FROM USER_CONSTRAINTS WHERE TABLE_NAME = "USER"."VW_X";

什么都不返回，这个：

SELECT a.table_name, 
     a.column_name, 
     a.constraint_name, 
     c.owner, 
     c.r_owner, 
     c_pk.table_name r_table_name, 
     c_pk.constraint_name r_pk, 
     c.status
FROM all_cons_columns a
JOIN all_constraints c 
ON a.owner = c.owner AND a.constraint_name = c.constraint_name
JOIN all_constraints c_pk 
ON c.r_owner = c_pk.owner AND c.r_constraint_name = c_pk.constraint_name
WHERE c_pk.table_name = 'VW_X' or c.table_name = 'VW_X';

（this帖子的最佳答案的变体）返回四个约束，所有这些约束的状态为'DISABLED'。

我调查了ALTER VIEW（这个名字听起来很有前途），但它似乎并不是我想要的。

有什么建议吗？

注意： 可能可能在提供的示例代码中存在一些语法错误。这些是模型，为了简单起见，出于职业偏执，大约十几个不相关的专栏已被删除，名称也被更改。

修改这是Oracle11g

修改我发现的解决方案是

-- drop view.
DROP VIEW "USER"."VW_X" CASCADE CONSTRAINTS;
commit;

-- create view.
CREATE OR REPLACE VIEW "USER"."VW_X" AS (
SELECT id, 
       name, 
       decode(RIGHT_COLUMN, 1, 'T', 0, 'F') AS problem
FROM "USER"."TEST");
commit;

CASCADE CONSTRAINTS似乎是缺失的链接。我很确定这些限制会丢失，但我并不特别在意。

Answer 1

ALTER VIEW
AS
SELECT
[new column name] = wrongcolumn

Answer 2

这是一个解决方案，它会丢弃FK，创建视图，然后重新创建FK

  -- create view with unique constraint
  create or replace view v_foo 
  (id unique disable novalidate, val)
  as 
  select id, val from foo;

  -- create second view
  create or replace view v_bar
  (id, val)
  as
  (select id, val from bar);

  -- add FK to second view
  alter view v_bar
  add constraint v_bar_ref
  foreign key (id) references v_foo(id)
   disable novalidate;


  -- add a column, this fails b/c of FK constraint 
  create or replace view v_foo 
  (id unique disable novalidate, val, dummy)
  as 
  select id, val, 1 from foo;

  -- remove constraint
  alter view v_bar
  drop constraint v_bar_ref;

  -- make changes to view
  create or replace view v_foo 
  (id unique disable novalidate, val, dummy)
  as 
  select id, val, 1 from foo;

  -- recreate FK constraint
  alter view v_bar
  add constraint v_bar_ref
  foreign key (id) references v_foo(id)
   disable novalidate;

如何编辑现有视图中的列

2 个答案: