MYSQL dump and problems character encoding
Assuming your source data contained only English and Greek characters, and was mis-exported with an ISO-8859-1 to UTF-8 conversion (rather than an ISO-8859-7 to UTF-8 conversion), you can get your data back by first repeating the missed conversion the other way around, and then doing the right one.

You could use iconv for this (available on pretty much all Linux distributions, and on Windows via gnuwin32).

You'd do something like:

$ iconv -f UTF-8 -t ISO-8859-1 &lt; bad_dump_file.sql | \
  iconv -f ISO-8859-7 -t UTF-8 &gt; good_dump_file.sql


As an example:

$ echo -n $'\xC3'$'\x90' | iconv -f UTF-8 -t ISO-8859-1 | \
   iconv -f ISO-8859-7 -t UTF-8 | hexdump -C
00000000  ce a0                                             |Î |
00000002


And 0xCE 0xA0 is the right UTF-8 encoding for Π.