大约有 30,000 项符合查询结果（耗时：0.0546秒） [XML]
Delete all Duplicate Rows except for One in MySQL? [duplicate]
...e.
NB - You need to do this first on a test copy of your table!
When I did it, I found that unless I also included AND n1.id <> n2.id, it deleted every row in the table.
If you want to keep the row with the lowest id value:
DELETE n1 FROM names n1, names n2 WHERE n1.id > n2.id AND n...
Handling a Menu Item Click Event - Android
...icked, but I'm not sure how to do this. I've been reading through the android documentation, but my implementation isn't correct..and some guidance in the right direction would help. I've listed my code below and commented out my problem areas, I think I'm invoking the wrong method.
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Cost of len() function
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Calling len() on those data types is O(1) in CPython, the most common implementation of the Python language. Here's a link to a table that provides the algorithmic complexity of many different functions in CPython:
TimeCompl...
How can I get WebStorm to recognize Jasmine methods?
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its called karma-jasmine, they changed it just to help us find it
– Andrzej Rehmann
Dec 23 '14 at 19:03
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Why doesn't Haskell's Prelude.read return a Maybe?
...nertia and/or changing insights, another reason might be that it's aesthetically pleasing to have a function that can act as a kind of inverse of show. That is, you want that read . show is the identity (for types which are an instance of Show and Read) and that show . read is the identity on the ra...
MySQL select one column DISTINCT, with corresponding other columns
...STINCT results from the FirstName column, but I need the corresponding ID and LastName .
12 Answers
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Generating an MD5 checksum of a file
...md5(file_as_bytes(open(fname, 'rb'))).digest()) for fname in fnamelst]
Recall though, that MD5 is known broken and should not be used for any purpose since vulnerability analysis can be really tricky, and analyzing any possible future use your code might be put to for security issues is impossible...
How to use XPath in Python?
... some of this pain.
Manual resource handling. Note in the sample below the calls to freeDoc() and xpathFreeContext(). This is not very Pythonic.
If you are doing simple path selection, stick with ElementTree ( which is included in Python 2.5 ). If you need full spec compliance or raw speed and can...
Timer & TimerTask versus Thread + sleep in Java
...not release the lock, waiting will release the lock for the object wait is called upon.
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MYSQL OR vs IN performance
...elieve people who give their "opinion", science is all about testing and evidence.
I ran a loop of 1000x the equivalent queries (for consistency, I used sql_no_cache):
IN: 2.34969592094s
OR: 5.83781504631s
Update:
(I don't have the source code for the original test, as it was 6 years ago, though...