oracle oracle中的select语句，只读
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select statements in oracle with for read only
提问by
I have a Database Linksin Oracle, and when I query some data like: select * from kfilwrk@something for read only, I have an error: "missing keyword". I can just write select statement, but the problem is, I need to add for read onlybecause my selectstatement may change some data.
我在Oracle 中有一个数据库链接，当我查询一些数据时：，我有一个错误：“缺少关键字”。我可以只写select语句，但问题是，我需要添加，因为我的语句可能会改变一些数据。select * from kfilwrk@something for read onlyfor read onlyselect
UPD: when I write simple select statement and retrieve data, after that I close SQL Developer, it asks me to rollback or commit data. It means the select cursor updates some data
UPD：当我编写简单的选择语句并检索数据时，在关闭 SQL Developer 之后，它要求我回滚或提交数据。这意味着选择光标更新了一些数据
回答by Andreas Fester
The syntax is WITH READ ONLY, not FOR READ ONLYand it can only be used with sub queries:
语法是WITH READ ONLY, notFOR READ ONLY并且它只能用于子查询：
SQL> CREATE DATABASE LINK MyLink CONNECT TO HR IDENTIFIED BY HR USING 'sampleHost:1521/XE';
SQL> SELECT COUNT(*) FROM (SELECT * FROM Dual@MyLink WITH READ ONLY);
COUNT(*)
----------
1
See also http://docs.oracle.com/database/121/SQLRF/statements_10002.htm#SQLRF55295:
另见http://docs.oracle.com/database/121/SQLRF/statements_10002.htm#SQLRF55295：
subquery_restriction_clauseThe subquery_restriction_clause lets you restrict the subquery in one of the following ways:
WITH READ ONLYSpecify WITH READ ONLY to indicate that the table or view cannot be updated.
subquery_restriction_clausesubquery_restriction_clause 允许您通过以下方式之一限制子查询：
WITH READ ONLY指定 WITH READ ONLY 指示不能更新表或视图。
Alternatively, you can set your transaction into read only mode:
或者，您可以将事务设置为只读模式：
SET TRANSACTION READ ONLY; -- Read only
...
SET TRANSACTION ISOLATION LEVEL READ COMMITTED; -- back to default (read committed)
回答by thatjeffsmith
If you query over a DB_LINK the database assumes there are transactions to COMMIT on close.
如果您通过 DB_LINK 查询，则数据库假定关闭时有要 COMMIT 的事务。
Also, SQL Developer has a shared connection for the Worksheet and the Database Navigator/Object Editors. So if you had opened a table and changed a record - that's on the same connection as your SELECT query on the worksheet.
此外，SQL Developer 具有用于工作表和数据库导航器/对象编辑器的共享连接。因此，如果您打开了一个表并更改了一条记录 - 这与您在工作表上的 SELECT 查询位于同一连接上。
