大约有 40,000 项符合查询结果（耗时：0.0259秒） [XML]
FIND_IN_SET() vs IN()
...FROM orders
CROSS JOIN
(
SELECT 1 AS pos
UNION ALL
SELECT 2 AS pos
UNION ALL
SELECT 3 AS pos
UNION ALL
SELECT 4 AS pos
UNION ALL
SELECT 5 AS pos
) q
JOIN company
ON companyID = CAST(NULLIF(SUBSTRI...
Select distinct values from a table field
...ant any ordering to be applied to a query, not even the default ordering, call order_by() with no parameters.
and distinct() in the note where it discusses issues with using distinct() with ordering.
To query your DB, you just have to call:
models.Shop.objects.order_by().values('city').distinct(...
Arrays vs Vectors: Introductory Similarities and Differences [closed]
...ze; you can't resize an array in C++ (unless it's an array of POD and it's allocated with malloc);
their size must be a compile-time constant unless they are allocated dynamically;
they take their storage space depending from the scope where you declare them;
if dynamically allocated, you must expli...
Where is the “Create Unit Tests” selection?
I have installed the new Visual Studio 2012 Ultimate.
9 Answers
9
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C multi-line macro: do/while(0) vs scope block [duplicate]
...use of function-style macros uniform with the
use of ordinary functions in all contexts.
Consider the following code sketch
if (<condition>)
foo(a);
else
bar(a);
where 'foo' and 'bar' are ordinary functions. Now imagine that you'd
like to replace function 'foo' with a macro of the abov...
Java Swing revalidate() vs repaint()
...n where I often want to replace the contents of a JPanel. To do this, I'm calling removeAll() , then adding my new content, then calling revalidate() .
...
Log.INFO vs. Log.DEBUG [closed]
...
I usually try to use it like this:
DEBUG: Information interesting for Developers, when trying to debug a
problem.
INFO: Information interesting for Support staff trying to figure out the context of a given error
WARN to FATAL: P...
CSS display: inline vs inline-block [duplicate]
...s and padding, but not top & bottom
cannot have a width and height set
allow other elements to sit to their left and right.
see very important side notes on this here.
Block elements:
respect all of those
force a line break after the block element
acquires full-width if width not defined
Inli...
Resque vs Sidekiq? [closed]
...ns out of the box.
Cons
[huge] requires thread-safety of your code and all dependencies. If you run thread-unsafe code with threads, you're asking for trouble;
works on some rubies better than others (jruby is recommended, efficiency on MRI is decreased due to GVL (global VM lock)).
...
Interface vs Abstract Class (general OO)
...
While your question indicates it's for "general OO", it really seems to be focusing on .NET use of these terms.
In .NET (similar for Java):
interfaces can have no state or implementation
a class that implements an interface must provide an implementation of all the methods of tha...