oracle 错误：ORA-01730：指定的列名数量无效
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error: ORA-01730: invalid number of column names specified
提问by Ralph Blackk
Please help. I want to create an object view from the ffl tables but i keep getting the above error and can't find any solution.
请帮忙。我想从 ffl 表创建一个对象视图，但我不断收到上述错误并且找不到任何解决方案。
create table COPY_BOOK (
NUM number(4,0),
DATE_Purchase date,
PRICE number(5,2),
LOAN_code varchar2(20) ,
STATUS varchar2(15) check (STATUS in ('GOOD','DAMAGED')),
CONSTRAINT CP_PK primary key (num) ,
constraint Loan_code_D check (LOAN_CODE in ('NO', 'LOAN'))
);
create or replace type copy_book_t as object(
num number(4, 0),
loan_code varchar2 (20)
);
/
create or replace view Vcopy_book of copy_book_t
with object oid (num)
as select cb.num, cb.date_purchase, cb.price, cb.loan_code, cb.status
from copy_book cb;
/
Is there a problem with the type definition?
类型定义有问题吗？
回答by Alex Poole
From the documentation:
从文档：
The procedure for defining an object view is:
Define an object type, where each attribute of the type corresponds to an existing column in a relational table.
Write a query that specifies how to extract the data from the relational table. Specify the columns in the same order as the attributes in the object type.
定义对象视图的过程是：
定义对象类型，其中该类型的每个属性对应于关系表中的现有列。
编写一个查询，指定如何从关系表中提取数据。按照与对象类型中的属性相同的顺序指定列。
You have created your object type with two attributes, but you're trying to populate it with five columns from your relational table.
您已经创建了具有两个属性的对象类型，但您正试图用关系表中的五列填充它。
You either need to change your object type to have the same five attributes (demo), or only select the numand loan_codecolumns in the view (demo).
您需要将对象类型更改为具有相同的五个属性 ( demo)，或者仅选择视图中的num和loan_code列 ( demo)。
Incidentally, the documentationalso recommends using with object identifierrather than with object oid.
顺便说一句，文档还建议使用with object identifier而不是with object oid.
