[yunqa.de] Re: D2007-D2010: corrupted text in database
- From: Delphi Inspiration <delphi@xxxxxxxx>
- To: yunqa@xxxxxxxxxxxxx
- Date: Sun, 24 Jan 2010 21:34:56 +0100
At 15:40 24.01.2010, Ïåòðîâ Äìèòðèé Þðüåâè÷ wrote:
>The databases created with same code in Delphi 2007 and Delphi 2010 appears to
>be incompatible when using Russian characters.
Before I point out the error in your code below, please know that database
files created by DISQLite3 are compatible accross Delphi versions (D4 up to
D2010 at the time of this writing) as well as accross different platforms
(SQLite applications on Windows, Linux, etc.).
>Example with source code: http://www.fox-manager.com.ua/download/db.zip
>For Example this code runs great in D2007 and D2010, but when I try to read a
>database created in D2007 in a program compiled in D2010 I get corrupted text:
>
>SQL := 'Create table if not exists Test (SomeText string);';
>DB.Execute(SQL);
The above code is wrong and D2010 results in the following compiler warning:
[DCC Warning] MainUnit.pas(39): W1057 Implicit string cast from 'string' to
'UTF8String'
Reason:
The TDISQLite3Database.Execute methods asks for a Utf8String, hence the SQL you
pass to it must be in UTF-8 encoding. However, literal strings default to
UnicodeString in D2010 but to ANSI in D2007.
Solution:
To solve your problem, use the equivalent UnicodeString / WideString function:
TDISQLite3Database.Execute16(const SQL: UnicodeString);
^^
This takes a UTF-16 LE encoded string (UnicodeString / WideString) and works
with both D2007 and D2010.
Sidebar:
While I do not speak Russian, the characters in the example do not look
Cyrillic to me in either D2007 or D2010. However, this might be due to my
language settings. Anyway, please ensure that you type in the correct literal
strings. In D2010, this might result in UTF-8 encoded source code units,
depending on your system locale.
In my experience, literal Unicode characters and strings are generally not well
preseverd accross Delphi versions, especially when opening and reopening them
with Unicode and non-Unicode versions of Delphi or accross different locales.
If you really need to support multiple Delphi versions reliably, it might be
best to load literal strings from external sources or store them as Unicode
code point arrays and create the strings dynamically.
Ralf
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