Oracle 中的 NLS_CHARACTERSET WE8ISO8859P1 和 UTF8 问题
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NLS_CHARACTERSET WE8ISO8859P1 and UTF8 issues in Oracle
提问by user958573
I am currently using a Database in oracle which has NLS_CHARACTERSET WE8ISO8859P1 so lets say I store a value in varchar2 field which is ma? (accented character) so in database it gets stored as ma?? . Now when I try to retrieve it with query select * from table where fieldValue = 'ma?' it returns 0 rows, and then when i try to insert it again it gives me a constraint error saying value already exist.
我目前在 oracle 中使用一个数据库，它有 NLS_CHARACTERSET WE8ISO8859P1 所以可以说我在 varchar2 字段中存储了一个值，它是 ma？（重音字符）所以在数据库中它被存储为 ma?? . 现在，当我尝试使用查询 select * from table where fieldValue = 'ma?' 检索它时 它返回 0 行，然后当我尝试再次插入它时，它给了我一个约束错误，说值已经存在。
How to overcome such situation. I am doing this via Java code
如何克服这种情况。我正在通过 Java 代码执行此操作
采纳答案by Multisync
http://docs.oracle.com/cd/B19306_01/server.102/b14225/ch2charset.htm#g1009784
http://docs.oracle.com/cd/B19306_01/server.102/b14225/ch2charset.htm#g1009784
Oracle Character Set Name: WE8ISO8859P1
Description: Western European 8-bit ISO 8859 Part 1
Region: WE (Western Europe)
Number of Bits Used to Represent a Character: 8
Oracle 字符集名称：WE8ISO8859P1
描述：西欧 8 位 ISO 8859 第 1 部分
区域：WE（西欧）
用于表示字符的位数：8
On the other hand, UTF-8 uses several bytes to store a symbol.
另一方面，UTF-8 使用几个字节来存储一个符号。
If your database uses WE8ISO8859P1 and the column type is from VARCHAR group (not NVARCHAR) and you're inserting a symbol which code > 255, this symbol will be transformed to WE8ISO8859P1 and some information will be lost.
如果您的数据库使用 WE8ISO8859P1 并且列类型来自 VARCHAR 组（不是 NVARCHAR），并且您插入的符号代码 > 255，则该符号将转换为 WE8ISO8859P1 并且一些信息将丢失。
To put it simply, if you're inserting UTF-8 into a db with single-byte character set, your data is lost.
简而言之，如果您将 UTF-8 插入到具有单字节字符集的数据库中，您的数据就会丢失。
The link above describes different scenarios how to tackle this issue.
上面的链接描述了如何解决这个问题的不同场景。
You can also try Oracle asciistr/unistrfunctions, but in general it's not a good way to deal with such problems.
也可以试试oracle asciistr/ unistrfunctions，但一般来说不是很好的处理此类问题的方法。
