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When and why are database joins expensive?
...t of multi-column joins and radically reducing the cost of joins involving string comparisons. Not only will vastly more fit in cache, there's a lot less disk reading to do.
Moreover, a good optimiser will choose the most restrictive condition and apply it before it performs a join, very effective...
C# getting the path of %AppData%
...ent.GetFolderPath(Environment.SpecialFolder.ApplicationData) returns empty string for me (IIS 7, VS 2011). Problem solved using Simon_Weaver solution - mapping using MapPath.
– Mike Keskinov
May 21 '12 at 19:16
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RedirectToAction with parameter
... the URL "/100", while new {groupId = 100} might be interpreted as a query string (as was mentioned above), resulting in the URL "?groupId=100".
– jakobinn
Jan 27 '19 at 12:57
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C++, Free-Store vs Heap
Dynamic allocations with new/delete are said to take place on the free-store , while malloc/free operations use the heap .
I'd like to know if there is an actual difference, in practice.
Do compilers make a distinction between the two terms? ( Free store and Heap , not new/malloc )
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Does java have a int.tryparse that doesn't throw an exception for bad data? [duplicate]
C# has Int.TryParse: Int32.TryParse Method (String, Int32%)
3 Answers
3
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Combine Date and Time columns using python pandas
...ng read_csv using parse_dates=[['Date', 'Time']].
Assuming these are just strings you could simply add them together (with a space), allowing you to apply to_datetime:
In [11]: df['Date'] + ' ' + df['Time']
Out[11]:
0 01-06-2013 23:00:00
1 02-06-2013 01:00:00
2 02-06-2013 21:00:00
3 02...
Returning a value from thread?
... Program
{
static bool done = false;
static void Main(string[] args)
{
BackgroundWorker bg = new BackgroundWorker();
bg.DoWork += new DoWorkEventHandler(bg_DoWork);
bg.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bg_RunWork...
All permutations of a Windows license key
... Nice! It never ocurred to me that you could use operator.mod to do string formatting too.
– Tom
Feb 4 '13 at 22:25
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Get Maven artifact version at runtime
...perties, falling back to getting it from the manifest
public synchronized String getVersion() {
String version = null;
// try to load from maven properties first
try {
Properties p = new Properties();
InputStream is = getClass().getResourceAsStream("/META-INF/maven/com....
Write string to text file and ensure it always overwrites the existing content.
I have a string with a C# program that I want to write to a file and always overwrite the existing content. If the file isn't there, the program should create a new file instead of throwing an exception.
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