大约有 43,000 项符合查询结果（耗时：0.0550秒） [XML]
Solving “Who owns the Zebra” programmatically?
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In Prolog, we can instantiate the domain just by selecting elements from it :) (making mutually-exclusive choices, for efficiency). Using SWI-Prolog,
select([A|As],S):- select(A,S,S1),select(As,S1).
select([],_).
left_of(A,B,C):- append(_,[A,B|_],C).
next_to(A,B,C):- l...
What is the difference between Views and Materialized Views in Oracle?
... you. The downside of a view is that its performance depends on how good a select statement the view is based on. If the select statement used by the view joins many tables, or uses joins based on non-indexed columns, the view could perform poorly.
Materialized views
They are similar to regular vi...
How to get first record in each group using Linq
...roup element by element.F1
into groups
select groups.OrderBy(p => p.F2).First();
share
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How do I convert a column of text URLs into active hyperlinks in Excel?
...y name itself HyperAdd.
Sub HyperAdd()
'Converts each text hyperlink selected into a working hyperlink
For Each xCell In Selection
ActiveSheet.Hyperlinks.Add Anchor:=xCell, Address:=xCell.Formula
Next xCell
End Sub
When you're finished pasting your macro, click Close and Re...
querySelector and querySelectorAll vs getElementsByClassName and getElementById in JavaScript
I would like to know what exactly is the difference between querySelector and querySelectorAll against getElementsByClassName and getElementById ?
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What is meant by Resource Acquisition is Initialization (RAII)?
...s piece of code:
void fn(const std::string& str)
{
std::vector<char> vec;
for (auto c : str)
vec.push_back(c);
// do something
}
when you create a vector and you push elements to it, you don't care about allocating and deallocating such elements. The vector uses new ...
Delete with Join in MySQL
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Since you are selecting multiple tables, The table to delete from is no longer unambiguous. You need to select:
DELETE posts FROM posts
INNER JOIN projects ON projects.project_id = posts.project_id
WHERE projects.client_id = :client_id
...
C++ preprocessor __VA_ARGS__ number of arguments
...VA_ARGS__), __VA_ARGS__))
void sum(int numargs, ...);
int main(int argc, char *argv[]) {
SUM(1);
SUM(1, 2);
SUM(1, 2, 3);
SUM(1, 2, 3, 4);
return 1;
}
void sum(int numargs, ...) {
int total = 0;
va_list ap;
printf("sum() called with %d params:", numargs);
...
Code snippet or shortcut to create a constructor in Visual Studio
...a C# project.
So how to make a constructor
Press Ctrl+K and then Ctrl+X
Select Visual C#
Select ctor
Press Tab
Update: You can also right-click in your code where you want the snippet, and select Insert Snippet from the right-click menu
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What is :: (double colon) in Python when subscripting sequences?
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TL;DR
This visual example will show you how to a neatly select elements in a NumPy Matrix (2 dimensional array) in a pretty entertaining way (I promise). Step 2 below illustrate the usage of that "double colons" :: in question.
(Caution: this is a NumPy array specific example with...