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How to add column if not exists on PostgreSQL?
...statement:
DO $$
BEGIN
BEGIN
ALTER TABLE <table_name> ADD COLUMN <column_name> <column_type>;
EXCEPTION
WHEN duplicate_column THEN RAISE NOTICE 'column <column_name> already exists in <table_name>.';
END;
END;
$$
...
Slicing of a NumPy 2d array, or how do I extract an mxm submatrix from an nxn array (n>m)?
... with x[numpy.ix_([0,2],[1,3])]. This can save you from having to enter in all of those extra brackets.
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Why can I initialize a List like an array in C#?
... has a method named Add(...)
What happens is the default constructor is called, and then Add(...) is called for each member of the initializer.
Thus, these two blocks are roughly identical:
List<int> a = new List<int> { 1, 2, 3 };
And
List<int> temp = new List<int>();
...
How To Check If A Key in **kwargs Exists?
...efix variable. If it is given, then its value is being used.
This is generally a compact and readable recipe for writing wrappers for any kind of function: Always just pass-through arguments you don't understand, and don't even know if they exist. If you always pass through *args and **kwargs you m...
Setting up two different static directories in node.js Express framework
...nal (first) parameter to use() like so:
app.use("/public", express.static(__dirname + "/public"));
app.use("/public2", express.static(__dirname + "/public2"));
That way you get two different directories on the web that mirror your local directories, not one url path that fails over between two lo...
How to iterate for loop in reverse order in swift?
... an array with one trillion Ints!
Test:
var count = 0
for i in lazy(1...1_000_000_000_000).reverse() {
if ++count > 5 {
break
}
println(i)
}
For Swift 2.0 in Xcode 7:
for i in (1...10).reverse() {
print(i)
}
Note that in Swift 2.0, (1...1_000_000_000_000).reverse(...
cpuid汇编指令 - C/C++ - 清泛网 - 专注C/C++及内核技术
... cpuid
cmp eax, 80000004h
jb not_supported
mov di, offset CPU_name
mov eax, 80000002h
cpuid
call save_string
mov eax, 80000003h
cpuid
...
Automatically add newline at end of curl response body
...or a curl request doesn't contain a trailing newline, I end up with this really annoying condition where the shell prompt is in the middle of the line, and escaping is messed up enough that when I put the last curl command on the screen, deleting characters from that curl command deletes the wrong c...
iPhone: How to get current milliseconds?
... it like this: NSTimeInterval myInterval = NSDate.timeIntervalSince1970;// all those brackets are really old fashioned if you ask me.
– Pizzaiola Gorgonzola
Oct 2 '13 at 13:27
...
Get a CSS value with JavaScript
...
Somewhat off topic: some (all?) shorthand css properties are not accessible in JavaScript. E.g. you can get padding-left but not padding. JSFiddle
– David Winiecki
May 9 '14 at 21:10
...