大约有 31,500 项符合查询结果（耗时：0.0451秒） [XML]
Is it fine to have foreign key as primary key?
...
Foreign keys are almost always "Allow Duplicates," which would make them unsuitable as Primary Keys.
Instead, find a field that uniquely identifies each record in the table, or add a new field (either an auto-incrementing integer or a GUID) to act as the p...
How can I return to a parent activity correctly?
...ent to it.
Therefore, the system is forced to recreate activity A (i.e. calling onCreate) even if the task stack is handled correctly.
To fix this problem you need to change the manifest, adding the following attribute to the A activity declaration:
android:launchMode="singleTop"
Note: calling...
get and set in TypeScript
...
})();
So to use it,
var myFoo = new foo();
if(myFoo.bar) { // calls the getter
myFoo.bar = false; // calls the setter and passes false
}
However, in order to use it at all, you must make sure the TypeScript compiler targets ECMAScript5. If you are running the command line compile...
Turn a string into a valid filename?
I have a string that I want to use as a filename, so I want to remove all characters that wouldn't be allowed in filenames, using Python.
...
How can I find the number of arguments of a Python function?
...ms = sig.parameters
print(params['kwarg1']) # prints: kwarg1=20
Additionally, you can call len on sig.parameters to also see the number of arguments this function requires:
print(len(params)) # 3
Each entry in the params mapping is actually a Parameter object that has further attributes makin...
How to view the assembly behind the code using Visual C++?
...
There are several approaches:
You can normally see assembly code while debugging C++ in visual studio (and eclipse too). For this in Visual Studio put a breakpoint on code in question and when debugger hits it rigth click and find "Go To Assembly" ( or press CTRL+ALT...
How can I check if a Perl array contains a particular value?
...For the record, this code still does iterate through the array. The map{} call simply makes that iteration very easy to type.
– Kenny Wyland
Mar 3 '12 at 23:09
3
...
String.replaceAll without RegEx
I'd like to replace all instances of a substring in a string but String.replaceAll() only accepts a pattern. The string that I have came from a previous match. Is it possible to add escapes to the pattern that I have or is there a version of replaceAll() in another class which accepts a literal ...
Standardize data columns in R
I have a dataset called spam which contains 58 columns and approximately 3500 rows of data related to spam messages.
15 ...
How to install Google Play Services in a Genymotion VM (with no drag and drop support)?
How can I install Google Play Services in a Genymotion emulator with no drag and drop support?
17 Answers
...