需要根据列的内容更改单列中的很多值

Question

我有一个数据库，其中包含的列完全包含指向播客音频文件的URL。几乎所有的格式都是http://abcdefgh.abcd.ca/podcasting/audio/YYYYMMDD-HHMMSS-to-YYYMMDD-HHMMSS.mp3。

问题是我们现在在/ audio /文件夹中有很多文件，需要很长时间才能在Windows资源管理器中加载该文件夹。因此，我们希望将它们全部移到文件夹中，例如http://abcdefgh.abcd.ca/podcasting/audio/20060321-140000-to-20000321-150000.mp3被移动到http://abcdefgh.abcd.ca/podcasting/audio/2006/20060321-140000-to-20000321-150000.mp3，我们必须更新数据库中的所有URL以反映新的文件夹结构。我们有从2006年到2015年这个命名约定的文件，并且在2015年9月左右我们进行了切换，以便所有新播客自动使用年份文件夹结构并且不需要更新。

我对SQL不太熟悉 - 这是我工作的一部分，但在聘用时很“高兴”。反正我的尝试是这样的：

/*urls are in structure of = 'http://abcdefgh.abcd.ca/audio/YYYYMMDD-HHMMSS-to-YYYYMMDD-HHMMSS.mp3 but then some aren't in this format which we ignore. All urls are in the column of the table named "url"*/ 
UPDATE table.podcast_episodes 
SET url = CASE 
    WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2006____-______-to-%.mp3' THEN url = concat(substring(url,1,41),'2006/',substring(url FROM 42)) 
    WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2007____-______-to-%.mp3' THEN url = concat(substring(url,1,41),'2007/',substring(url FROM 42)) 
    WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2008____-______-to-%.mp3' THEN url = concat(substring(url,1,41),'2008/',substring(url FROM 42)) 
    WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2009____-______-to-%.mp3' THEN url = concat(substring(url,1,41),'2009/',substring(url FROM 42)) 
    WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2010____-______-to-%.mp3' THEN url = concat(substring(url,1,41),'2010/',substring(url FROM 42)) 
    WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2011____-______-to-%.mp3' THEN url = concat(substring(url,1,41),'2010/',substring(url FROM 42)) 
    WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2012____-______-to-%.mp3' THEN url = concat(substring(url,1,41),'2011/',substring(url FROM 42)) 
    WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2013____-______-to-%.mp3' THEN url = concat(substring(url,1,41),'2012/',substring(url FROM 42)) 
    WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2014____-______-to-%.mp3' THEN url = concat(substring(url,1,41),'2014/',substring(url FROM 42)) 
    WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2015____-______-to-%.mp3' THEN url = concat(substring(url,1,41),'2015/',substring(url FROM 42)) 
    /* do nothing */ 
    ELSE url= url 
END 

它的问题是它只是设置的URL字段为0时，它的case语句相匹配，或1当它击中了“其他”的声明，这是不是我想。

Answer 1

如果这是一次性工作，则不需要使用SQL。你可以转储表：

mysqldump -u user -p database table > dump.sql 

使文本替换：

sed -i 's|\(http://abcdefgh.abcd.ca/podcasting/audio/\)\([0-9]\{4\}\)\([-to0-9]*\.mp3\)|\1\2/\2\3|g' dump.sql 

，并导入表背：

mysqlimport -u user -p database table < dump.sql 

这些命令是为Linux/Unix的。如果你在Windows上，你可以使用你最喜欢的工具。

Answer 2

因为您没有正确使用您的ELSE或CASE语句。格式是

CASE WHEN url LIKE ... THEN (the concatenated value that you're setting url to). 

你不这样做

THEN url = (concatenated value you're creating) 

，因为它会失败，你看到它失败的方式。如果你做了这样的细微修改：

UPDATE podcast_episodes 
SET url = CASE 
WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2006____-______-to-%.mp3' THEN concat(substring(url,1,41),'2006/',substring(url FROM 42)) 
WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2007____-______-to-%.mp3' THEN concat(substring(url,1,41),'2007/',substring(url FROM 42)) 
WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2008____-______-to-%.mp3' THEN concat(substring(url,1,41),'2008/',substring(url FROM 42)) 
WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2009____-______-to-%.mp3' THEN concat(substring(url,1,41),'2009/',substring(url FROM 42)) 
WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2010____-______-to-%.mp3' THEN concat(substring(url,1,41),'2010/',substring(url FROM 42)) 
WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2011____-______-to-%.mp3' THEN concat(substring(url,1,41),'2010/',substring(url FROM 42)) 
WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2012____-______-to-%.mp3' THEN concat(substring(url,1,41),'2011/',substring(url FROM 42)) 
WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2013____-______-to-%.mp3' THEN concat(substring(url,1,41),'2012/',substring(url FROM 42)) 
WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2014____-______-to-%.mp3' THEN concat(substring(url,1,41),'2014/',substring(url FROM 42)) 
WHEN url LIKE 'http://abcdefgh.abcd.ca/podcasting/audio/2015____-______-to-%.mp3' THEN concat(substring(url,1,41),'2015/',substring(url FROM 42)) 
/* do nothing */ 
ELSE url 
END 

然后它应该工作。 Here's a SQL fiddle to show the difference