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When to use SELECT … FOR UPDATE?
...ends on the concurrency control your database system is using.
MyISAM in MySQL (and several other old systems) does lock the whole table for the duration of a query.
In SQL Server, SELECT queries place shared locks on the records / pages / tables they have examined, while DML queries place update ...
How to implement a tree data-structure in Java? [closed]
...
Here:
public class Tree<T> {
private Node<T> root;
public Tree(T rootData) {
root = new Node<T>();
root.data = rootData;
root.children = new ArrayList<Node<T>>();
}
public static class Node<T> {
priva...
Get root view from current activity
I know how to get the root view with View.getRootView() . I am also able to get the view from a button's onClick event where the argument is a View . But how can I get the view in an activity ?
...
Non-recursive depth first search algorithm
...
DFS:
list nodes_to_visit = {root};
while( nodes_to_visit isn't empty ) {
currentnode = nodes_to_visit.take_first();
nodes_to_visit.prepend( currentnode.children );
//do something
}
BFS:
list nodes_to_visit = {root};
while( nodes_to_visit isn't ...
My Git repository is in the wrong root directory. Can I move it? (../ instead of ./)
...or so ago I ran the command in the directory one directory higher than the root of my project.
9 Answers
...
os.walk without digging into directories below
... os.path.isdir(some_dir)
num_sep = some_dir.count(os.path.sep)
for root, dirs, files in os.walk(some_dir):
yield root, dirs, files
num_sep_this = root.count(os.path.sep)
if num_sep + level <= num_sep_this:
del dirs[:]
It works just like os.walk, but y...
How do I list all cron jobs for all users?
...
You would have to run this as root, but:
for user in $(cut -f1 -d: /etc/passwd); do crontab -u $user -l; done
will loop over each user name listing out their crontab. The crontabs are owned by the respective users so you won't be able to see another u...
List files by last edited date
...ort | cut -f 2- -d ' '
The result looks a lot like ls -l:
-rw-r--r-- 1 root root 3892 08/11/2009 11:03:36 /usr/share/man/man1/xmllint.1.gz
-rw-r--r-- 1 root root 22946 08/13/2009 11:59:20 /usr/share/man/man1/curl.1.gz
-rw-r--r-- 1 root root 728 08/17/2009 12:0...
正则表达式 30 分钟入门教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...：deerchao 转载请注明来源
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Sass combining parent using ampersand (&) with type selectors
...his has been possible since Sass 3.3.0.rc.1 (Maptastic Maple).
The @at-root directive causes one or more rules to be emitted at the root of the document, rather than being nested beneath their parent selectors.
We can combine the @at-root directive along with interpolation #{} to arrive at the...