A field in java his type is GUID. In db2 his type is char for data type. I don't understand why (x'00345C9101600000018323B4F1311964BB' < x'00345C9101600000018323B4F1311964BB01') is false. is this not the comparation of Hexadecimal?
Thanks for your help.
Since the SQL data type is character, string comparison rules apply, so the shorter string is padded with spaces on the right. The ASCII code for the space character is x'20', which is greater than x'01'.
For the assigned hex value to be compared is too large to be calculated as the memory assigned for variable is limited, due to this it is throwing garbage value which is resulting to false result.
Related
I have this kind of symbols in db table (Наиме) , and I don't know who inserted this data to table.Is there any way to convert them to cyrillic ?
Yes, you can do the conversion. Since you haven't mentioned any langauge, so the logic is given:
Assuming the string length is even, take two immediate characters.
Combine the underlying byte values of two characters to give a 16 bit value. This gives you the multi-byte value of Cryllic character. You can decode the value to give its representation using a proper decoding format like utf-8.
Repeat points 1 and 2 for next two characters until the end of string.
If you want, you can implement it in any language of your choice.
When working in the Moovweb SDK, length("çãêá") is expected to return 4, but instead returns 8. How can I ensure that the length function works correctly when using Unicode characters?
This is a common issue with Unicode characters and the length() function using the wrong character set. To fix it you need to set the charset_determined variable to make sure the correct character set is being used before making the call to length(), like so in your tritium code:
$charset_determined = "utf-8"
# your call to length() here
In Unicode, there is no such thing as a length of a string or "number of characters". All this comes from ASCII thinking.
You can choose from one of the following, depending what you exactly need:
For cursor movement, text selection and alike, grapheme clusters shall be used.
For limiting the length of a string in input fields, file formats, protocols, or databases, the length is measured in code units of some predetermined encoding. The reason is that any length limit is derived from the fixed amount of memory allocated for the string at a lower level, be it in memory, disk or in a particular data structure.
The size of the string as it appears on the screen is unrelated to the number of code points in the string. One has to communicate with the rendering engine for this. Code points do not occupy one column even in monospace fonts and terminals. POSIX takes this into account.
There is more info in http://utf8everywhere.org
In a program I have used a function RPAD() to format data coming from DB2 db.
In one instance the value was Ãmber. The following function:
RPAD('Ãmber',10,' ')
gives 9 characters only.
The ASCII value of 'Ã' is 195. I am not able to understand the reason for this behaviour.
Could someone share their experience.
Thanks
By default, DB2 will consider the length of à to be 2, likely because it is counting bytes rather than characters.
values(LENGTH('Ãmber'))
6
You can override it for LENGTH and many other functions
values(LENGTH('Ãmber', CODEUNITS16))
5
Unfortunately, RPAD does not take a parameter like this. I'm guessing this might be because the function was added for Oracle compatibility rather than on its own merits.
You could write your own RPAD function as a stored procedure or UDF, or just handle it with a CASE statement if this is the only place where you need it.
I want to use Unicode in my code. My Unicode value is 0100 and I am adding my Unicode string \u with my value. When I use string myVal="\u0100", it's working, but when I use like below, it's not working. The value is looking like "\\u1000";. How do I resolve this?
I want to use it like the below one, because the Unicode value may vary sometimes.
string uStr=#"\u" + "0100";
There are a couple of problems here. One is that #"\u" is actually the literal string "\u" (can also be represented as "\u").
The other issue is that you cannot construct a string in the way you describe because "\u" is not a valid string by itself. The compiler is expecting a value to follow "\u" (like "\u0100") to determine what the encoded value is supposed to be.
You need to keep in mind that strings in .NET are immutable, which means that when you look at what is going on behind the scenes with your concatenated example (`#"\u"+"0100"), this is what is actually happening:
Create the string "\u"
Create the string "0100"
Create the string "\u0100"
So you have three strings in memory. In order for that to happen all of the strings must be valid.
The first option that comes to mind for handling those values is to actually parse them as integers, and then convert them to characters. Something like:
var unicodeValue = (char)int.Parse("0100",System.Globalization.NumberStyles.AllowHexSpecifier);
Which will give you the single Unicode character value. From there, you can add it to a string, or convert it to a string using ToString().
I am currently exploring the specification of the Digital Mars D language, and am having a little trouble understanding the complete nature of the primitive character types. The book Learn to Tango With D is similarly vague on the capabilities and limitations of the language in this area.
The types are given on the website as:
char; // unsinged 8 bit UTF-8
wchar; // unsigned 16 bit UTF-16
dchar; // unsigned 32 bit UTF-32
Since we know that most of the Unicode Transformation (UTF) Format encodings represent characters with a variable bit-width, does this mean that a char in D can only contain the values that will fit in 8 bits, or does it expand in the machine's physical memory when you give it double byte characters? Perhaps there is some other possibility, like automatic casting into the next most appropriate type as you overload the variable?
Let's say for example, I want to use the UTF-8 char in an editor and type in Chinese . Will it simply fall over, or is it able to deal with Unicode characters more 'correctly', like in C#? Would it still be necessary to provide glue code to allow working with any language supported by Unicode?
I'd appreciate any specific information you can offer on how these types work under the covers, and any general best practices advice on dealing with their limitations.
A single char or wchar represents an UTF code unit. This means that, by its own, a char in can either represent an ASCII symbol (0-127) or be part of an UTF-8 sequence representing an Unicode character (code point). Only the dchar type can represent an entire Unicode character, because there are more than 65536 code points in Unicode.
Casting one type of string type (string, wstring and dstring, which are simply dynamic arrays of the character types) will not automatically convert their contents to the respective UTF representation. In order to do this, you must use the functions toUTF8, toUTF16 and toUTF32 from std.utf (or toString / toString16 / toString32 from tango.text.convert.Utf if you use Tango).
Users have implemented string classes which will automatically use the most memory-efficient representation that can map each character to a single code unit. This allows quick slicing and indexing with a minimal memory overhead. One such implementation is mtext by Christopher E. Miller.
Further reading:
the String handling section in Wikipedia's entry on D
Text in D, by Daniel Keep