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Thread: Charlength()

  1. #1
    Join Date
    Mar 2006
    Posts
    56

    Unanswered: Charlength()

    Hello forum,

    I have difficulty convincing MySQL to count some 'exotic' characters in IPA as a single letter. My query goes like this:

    Code:
    SELECT vowel, CHAR_LENGTH(vowel)
      FROM
    (
          SELECT 'i' vowel FROM DUAL
    UNION SELECT 'ɪ' vowel FROM DUAL
    UNION SELECT 'u' vowel FROM DUAL
    UNION SELECT 'ʊ' vowel FROM DUAL
    UNION SELECT 'e' vowel FROM DUAL
    UNION SELECT 'ɜ' vowel FROM DUAL
    UNION SELECT 'ə' vowel FROM DUAL
    UNION SELECT 'ɔ' vowel FROM DUAL
    UNION SELECT '' vowel FROM DUAL
    UNION SELECT 'ʌ' vowel FROM DUAL
    UNION SELECT 'ɑ' vowel FROM DUAL
    UNION SELECT 'ɒ' vowel FROM DUAL) vowels;
    I used the CHAR_LENGTH function because LENGTH('ʊ') etc. return 2. I take this as evidence that many IPA symbols for English vowels are multi-byte. The above query is expected to return 1 for all rows but the results are like below. Where have I made mistakes?

    Code:
    +-------+--------------------+
    | vowel | CHAR_LENGTH(vowel) |
    +-------+--------------------+
    | i     |                  1 | 
    | ɪ    |                  2 | 
    | u     |                  1 | 
    | ʊ    |                  2 | 
    | e     |                  1 | 
    | ɜ    |                  2 | 
    | ə    |                  2 | 
    | ɔ    |                  2 | 
    |     |                  2 | 
    | ʌ    |                  2 | 
    | ɑ    |                  2 | 
    | ɒ    |                  2 | 
    +-------+--------------------+
    12 rows in set (0.00 sec)
    Thanks in advance!

  2. #2
    Join Date
    Jun 2007
    Location
    London
    Posts
    2,527
    It's strange because looking at the manual it seems to imply the opposite:
    Returns the length of the string str, measured in characters. A multi-byte character counts as a single character. This means that for a string containing five two-byte characters, LENGTH() returns 10, whereas CHAR_LENGTH() returns 5.
    Sadly I have no idea how you enter the Greek/Russian characters so I can't test it. Can you explain how you enter them? Does it produce the same results if you simplify things to:
    Code:
     SELECT CHAR_LENGTH('ʊ')

  3. #3
    Join Date
    Mar 2006
    Posts
    56
    Mike,

    I also read the manual. In fact, it was where I learnt that MySQL offers the multi-byte safe version of LENGTH().

    IPA (International Phonetic Alphabet) is not characters for Greek or Russian, nor is it for any specific language; it is a set of letters that represent phonetic values for theoretically any language on the earth. Most English dictionaries (including ones from Oxford and Cambridge) use this system to show the pronunciations of English words.

    To Enter:
    Simply copy & paste from web pages such as this:
    http://weston****ter.net/projects/ip...view/keyboard/

    Upps, I am not allowed to post a valid URL here?
    Please Google for this
    ipa keyboard inurl:weston

    Simplified Test:
    Code:
    mysql>  SELECT CHAR_LENGTH('ʊ');
    +-------------------+
    | CHAR_LENGTH('ʊ') |
    +-------------------+
    |                 2 | 
    +-------------------+
    1 row in set (0.01 sec)

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