oracle ORA-00955“名称已被现有对象使用”
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ORA-00955 "name is already used by an existing object"
提问by My-Name-Is
I need to modify an existing PK. Therefore I drop an recreate it.
我需要修改现有的 PK。因此我放弃了重新创建它。
ALTER TABLE B DROP CONSTRAINT PK_B;
ALTER TABLE B ADD CONSTRAINT PK_B PRIMARY KEY ("TYP", "NR", "HH", "QUART");
Unfortunately the last Statement will give me an error ORA-00955
不幸的是，最后一条语句会给我一个错误 ORA-00955
If I create the PK constraint like it was defined originally with:
如果我像最初定义的那样创建 PK 约束：
ALTER TABLE B ADD CONSTRAINT PK_B PRIMARY KEY ("TYP", "NR", "HH");
everything works fine.
一切正常。
回答by Lalit Kumar B
Perhaps there is an INDEXassociated with the PRIMARY KEY CONSTRAINT, and it is also named as PK_B.
也许有一个INDEX与 相关联PRIMARY KEY CONSTRAINT，它也被命名为PK_B。
You can check it as :
您可以将其检查为：
SELECT * FROM USER_INDEXES WHERE TABLE_NAME='<table_name>';
If that's true, then do :
如果这是真的，那么做：
ALTER INDEX "PK_B" RENAME TO "PK_XYZ";
Update : Regarding ALTER INDEXstatement, few important points as mentioned by Justin in the comments
更新：关于ALTER INDEX声明，贾斯汀在评论中提到的几个要点
Oracle implicitly creates an UNIQUEindex to support the PRIMARY KEY CONSTRAINT. Since, the index is of the same name that of the primary key, and now that the primary key is being modified, it is betterto drop and re-create the index again as per the definition of the old primary key.
Oracle 隐式地创建了一个UNIQUE索引来支持PRIMARY KEY CONSTRAINT. 由于索引与主键的名称相同，现在正在修改主键，最好根据旧主键的定义再次删除并重新创建索引。
My conclusion :
我的结论：
- The primary key constraint is enforced through a unique index.
- If Oracle already finds an index – unique or non-unique – it uses it for the primary key.
- If the index was initially created as non-unique, it will continue to show as non-unique, however it will actually be a unique index.
- 主键约束通过唯一索引强制执行。
- 如果 Oracle 已经找到了一个索引——唯一的或非唯一的——它会将它用作主键。
- 如果索引最初创建为非唯一索引，它将继续显示为非唯一索引，但实际上它是唯一索引。
A good demonstration and quite detailed on other aspects too, by Arup : Primary Keys Guarantee Uniqueness? Think Again.
一个很好的演示，并且在其他方面也非常详细，作者：Arup：主键保证唯一性？再想想。
回答by donsasikumar
I had the same issue where I had to do the following to delete reference to a table from the view whilst recreating the database from the scratch. I was searching for the same in tables and indexes first.
我遇到了同样的问题，我必须执行以下操作才能从视图中删除对表的引用，同时从头开始重新创建数据库。我首先在表和索引中搜索相同的内容。
connect sys/oracle as sysdba;
select * from all_tables
select * from all_indexes
(finally located the reference in the views)
select * from all_views where view_name like '%WKSTSTATE%';
drop view RUEGEN.WKSTSTATE;
