大约有 47,000 项符合查询结果(耗时:0.0440秒) [XML]

https://stackoverflow.com/ques... 

Random row selection in Pandas dataframe

Is there a way to select random rows from a DataFrame in Pandas. 6 Answers 6 ...
https://stackoverflow.com/ques... 

What is a good reason to use SQL views?

...one extra column active. If your system(s) have gazillion queries that do SELECT whatever FROM T_OLD WHERE whatever, you have two choices for the roll-out: 1) Cold Turkey - Change the DB, and at the same time, change, test and release numerous pieces of code which contained said query. VERY hard t...
https://stackoverflow.com/ques... 

Beautiful Soup and extracting a div and its contents by ID

... Beautiful Soup 4 supports most CSS selectors with the .select() method, therefore you can use an id selector such as: soup.select('#articlebody') If you need to specify the element's type, you can add a type selector before the id selector: soup.select('di...
https://stackoverflow.com/ques... 

Fragment onCreateView and onActivityCreated called twice

....getFragmentManager().findFragmentByTag(mTag); } public void onTabSelected(Tab tab, FragmentTransaction ft) { if (mFragment == null) { mFragment = Fragment.instantiate(mActivity, mClass.getName()); ft.replace(android.R.id.content, mFragment, mTag); } ...
https://stackoverflow.com/ques... 

jQuery: Best practice to populate drop down?

...emory (with a string variable) first and then append this string to parent select control should be more efficient, because this will cause only once page layout – Wint Jul 2 '15 at 14:41 ...
https://stackoverflow.com/ques... 

MySQL dump by query

... not mysqldump, but mysql cli... mysql -e "select * from myTable" -u myuser -pxxxxxxxxx mydatabase you can redirect it out to a file if you want : mysql -e "select * from myTable" -u myuser -pxxxxxxxx mydatabase > mydumpfile.txt Update: Original post asked if...
https://stackoverflow.com/ques... 

MySQL get the date n days ago as a timestamp

... DATE_SUB will do part of it depending on what you want mysql> SELECT DATE_SUB(NOW(), INTERVAL 30 day); 2009-06-07 21:55:09 mysql> SELECT TIMESTAMP(DATE_SUB(NOW(), INTERVAL 30 day)); 2009-06-07 21:55:09 mysql> SELECT UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL 30 day)); 1244433347 ...
https://stackoverflow.com/ques... 

Using async/await for multiple tasks

...ything but waiting. int[] ids = new[] { 1, 2, 3, 4, 5 }; Task.WaitAll(ids.Select(i => DoSomething(1, i, blogClient)).ToArray()); On the other hand, the above code with WaitAll also blocks the threads and your threads won't be free to process any other work till the operation ends. Recommende...
https://stackoverflow.com/ques... 

Cause of a process being a deadlock victim

I have a process with a Select which takes a long time to finish, on the order of 5 to 10 minutes. I am currently not using NOLOCK as a hint to the MS SQL database engine. At the same time we have another process doing updates and inserts into the same database and same tables. The first pr...
https://stackoverflow.com/ques... 

MySQL: Transactions vs Locking Tables

...ransactions vs locking tables to ensure database integrity and make sure a SELECT and UPDATE remain in sync and no other connection interferes with it. I need to: ...