Some unicode characters are represented as “?” mark when inserting to Oracle from Delphi

Question

I have written an application in Delphi 2010 that imports data from one database to another. I've done this before many times: From Access to Acces, Access to SQL Server. But now I have to import data from SQL Server 2005 to Oracle 10G. I do this by selecting all the rows from a table in SQL Server database and inserting them one by one to a table with the same structure in Oracle database. The import performs normally except for that I get question marks for some unicode characters. When I insert those characters in the database manually it shows them properly. It's something between Delphi and Oracle. I use UniDac component set for this purpose. Does anybody know the reason for those question marks?

Answer 1

Basically two possibilities: either the character encoding is wrong, or the software used to display the text is using a font (or set of fonts) that does not contain all the characters. To check this, copy some of the displayed text containing the problem characters into another program, like MS Word, and see if it displays them. Set Word to use Arial Unicode MS if needed.