Begin 
SET @str = tekst;
SET @str = replace(@str,"ó","o");
SET @str = replace(@str,"Ó","O");
SET @str = replace(@str,"ą","a");
SET @str = replace(@str,"Ą","A");
SET @str = replace(@str,"ę","e");
SET @str = replace(@str,"Ę","E");
SET @str = replace(@str,"ł","l");
SET @str = replace(@str,"Ł","L");
SET @str = replace(@str,"ż","z");
SET @str = replace(@str,"Ż","Z");
SET @str = replace(@str,"ź","z");
SET @str = replace(@str,"Ź","Z");
SET @str = replace(@str,"ć","c");
SET @str = replace(@str,"Ć","C");
return @str;
END