2015-08-17 14:18
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I'm trying to return a SUBSTR between two delimiters. The Problem is, that the second delimiter is non-unique in the whole string.


So I want to extract the string between "&[uniquedelimiter]=" and the next ":" after the unique delimiter. The occurrence of ":" in the string is variable.

Right now I'm using a double SUBSTRING_INDEX function, but I get errors if the string contains more than one ":".

SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(list_of_urls, '&[uniquedelimiter]=',-1),':')
FROM url_table;

I couldn't find a comparable solution on any Community.

Thank you so much for your help, Lars

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我正在尝试在两个分隔符之间返回一个SUBSTR。 问题是,第二个分隔符在整个字符串中是非唯一的。

示例: ; [uniquedelimiter] = texttoextract:sometext:someothertext

所以我想在“& [uniquedelimiter] =”和 next “之间提取字符串:” 在唯一分隔符之后。 字符串中“:”的出现是可变的。

现在我正在使用双SUBSTRING_INDEX函数,但如果字符串包含多个,则会出错 一个“:”。

  SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(list_of_urls,'& [uniquedelimiter] =', -  1),':')
FROM url_table; 
 <  / code>  


非常感谢你的帮助, Lars

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1条回答 默认 最新

  • duanfu1945 2015-08-17 14:32

    This seems to be working, maybe you can sort it, not sure:

        (POSITION('&[uniquedelimiter]=' IN url) + LENGTH('&[uniquedelimiter]=')),
        LOCATE(':', url, (POSITION('&[uniquedelimiter]=' IN url) + LENGTH('&[uniquedelimiter]='))) -
        (POSITION('&[uniquedelimiter]=' IN url) + LENGTH('&[uniquedelimiter]='))
    from bla

    My strategy was like this:

    SET @url                   = (SELECT url from bla limit 1);
    SET @pos_uniq_deli_start   = POSITION('&[uniquedelimiter]=' IN @url);
    SET @uniq_deli_length      = LENGTH('&[uniquedelimiter]=');
    SET @pos_uniq_deli_end     = @pos_uniq_deli_start + @uniq_deli_length;
    --                           LOCATE(char, field, offset)
    SET @pos_colon_after_deli  = LOCATE(':', @url, @pos_uniq_deli_end);
    SET @delta_unqi_del_colon  = @pos_colon_after_deli - @pos_uniq_deli_end;
    --            SUBSTRING(field, start_pos, length)
    SET @result = SUBSTRING(@url,@pos_uniq_deli_end, @delta_unqi_del_colon);
    SELECT @result;
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