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Is there an Oracle function that can recognize if a character is readable or not?

I would like to search a specific column for garbled characters. I know that this can typically be done with a regular expression. However, my database contains Japanese characters, so it is not just a simple matter of an [A-Z][0-9] pattern.

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What would constitute an "unreadable character" or a "garbled character"? What is the database character set? –  Justin Cave Sep 18 '12 at 1:43
The database character set is UTF-8. I guess garbled character is difficult to defined since it may still appear as japanese character but because it is already corrupted data it would be some squares, diamond and unreadable japanese. –  Nap Sep 18 '12 at 1:54
This is impossible to answer unless you list exactly which characters are acceptable. Unprintable characters may be fine on a system with the correct fonts installed. –  tblPhil Sep 18 '12 at 13:11

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I think the answer given the specifics is "no there is not." I would think, however, in Oracle you could use a regular expression perhaps to find fields with characters not in a specific set. See http://docs.oracle.com/cd/B19306_01/appdev.102/b14251/adfns_regexp.htm

I don't know how regex usage works with indexes on Oracle however.

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