大约有 30,000 项符合查询结果（耗时：0.0375秒） [XML]
Automatically deleting related rows in Laravel (Eloquent ORM)
...ete method, so if you are doing extra work on delete (for example - delete files), it will not run
– amosmos
Dec 22 '15 at 13:57
10
...
Join vs. sub-query
...s above 100,000. The thing seems to be memory usage and paging to the swap-file. A join would produce a very big amount of data, that may not fit into memory and must be paged into the swap-file. Whenever this is the case the query-times of small sub-selects like select * from a where a.x = (select ...
Efficiency of premature return in a function
...ying to optimize. For the major C-like languages (C, objC, C++, Java, C#, etc) and their usual compilers, will these two functions run just as efficiently? Is there any difference in the compiled code?
...
How to cast an Object to an int
...t;
Scenario 2: any numerical object
In Java Integer, Long, BigInteger etc. all implement the Number interface which has a method named intValue. Any other custom types with a numerical aspect should also implement Number (for example: Age implements Number). So you can:
int x = ((Number)yourOb...
Python: reload component Y imported with 'from X import Y'?
...esn't work because X not imported yet
Traceback (most recent call last):
File "<input>", line 1, in <module>
NameError: name 'X' is not defined
>>> import X
>>> print Y()
Test 1
>>> print X.Y()
Test 1
>>> reload( X ) # No effect on previous "from" st...
What are bitwise shift (bit-shift) operators and how do they work?
... programming. If you read a specification for a device or even some binary file formats, you will see bytes, words, and dwords, broken up into non-byte aligned bitfields, which contain various values of interest. Accessing these bit-fields for reading/writing is the most common usage.
A simple real...
What are the security risks of setting Access-Control-Allow-Origin?
... is automatically provided by the browser (cookies, cookie-based sessions, etc.), the requests triggered by the third party sites will use them too.
This indeed poses a security risk, particularly if you allow resource sharing not just for selected resources but for every resource. In this context ...
Adding an identity to an existing column
...s columns with this method. Adding/removing columns, changing nullability, etc. isn't allowed.
You'll need to drop foriegn keys before you do the switch and restore them after.
Same for WITH SCHEMABINDING functions, views, etc.
new table's indexes need to match exactly (same columns, same order, e...
Capturing console output from a .NET application (C#)
...of your application.
Process compiler = new Process();
compiler.StartInfo.FileName = "csc.exe";
compiler.StartInfo.Arguments = "/r:System.dll /out:sample.exe stdstr.cs";
compiler.StartInfo.UseShellExecute = false;
compiler.StartInfo.RedirectStandardOutput = true;
compiler.Start();
Console.Writ...
Why and not taking font-family and font-size from body?
...
In case you're wondering what other styles are defined, check out the CSS files in your resources. You can access them via the url above, or by looking in your res folder in the firefox directory (eg: c:\program files\mozilla firefox\res). These are the ones which may be affecting the styles of nor...