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Don Burleson Blog 







Single Quote Apostrophe Marks Change to Upside-Down Question Marks

Expert Oracle Database Tips by Donald BurlesonFebruary 10, 2015

Single Quote Apostrophe Marks Change to Upside Down Question Marks

Question: We are extracting columns from Oracle tables that contain single quote names with apostrophes:


The flat files are changing the quote marks (apostrophes) into upside-down question marks, displaying a special character ' as ¿

How do we avoid this?

Answer:  If you are on Windows, this is a "single quote" conversion to a upside-down question mark is a common problem may might be fixed by converting to a character set such as WE8MSWIN1252. 

Try this test in SQL*Plus:

 set nls_lang = WE8MSWIN1252
export nls_lang
spool myfile.txt
select last_name from mytab
spool off;

The very first step in diagnosing a special character in Oracle SQL output is to consult the Oracle National Language Support documentation for what character sets supports the single quote apostrophe on your OS flat files, usually a UNICODE type character set.

Next, read these important notes on testing "special characters" as part of your nls_lang setting.

As you see, Oracle will replace characters that are not within its character set with the upside-down question mark and your problem is that either the database or the flat files has an incorrect character set as defined by your nls_lang parameter.  The upside-down question mark means that the character set does not support the quote mark.   See MOSC Note 275138.1 (Cannot Map Unicode To Oracle Character) for complete resolution details.

An apostrophe is not really a "special" character, and internally, a single quote (apostrophe) is represented by an ASCII "0x27".  You need to choose a character set that includes single quotes.  

An Interweb search says that an apostrophe can be represented in the Windows WE8MSWIN1252 by at least four different codes:

  • 0xb4 - accent mark (´)
  • 0x91 - left single quotation mark (')
  • 0x92 - right single quotation mark (')
  • 0x27 - standard ASCII apostrophe (')  

Beware, the Windows single quote character (aka smart quote) is non-standard and it is is not contained in the WE8ISO8859P1 character set.

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