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“INSERT IGNORE” vs “INSERT … ON DUPLICATE KEY UPDATE”
...ly, which has some unexpected side effects:
A new auto-increment ID is allocated.
Dependent rows with foreign keys may be deleted (if you use cascading foreign keys) or else prevent the REPLACE.
Triggers that fire on DELETE are executed unnecessarily.
Side effects are propagated to replicas too....
How do I change the title of the “back” button on a Navigation Bar
...er statement.
UIBarButtonItem *newBackButton =
[[UIBarButtonItem alloc] initWithTitle:@"NewTitle"
style:UIBarButtonItemStyleBordered
target:nil
action:nil];
[[self na...
Is there a performance impact when calling ToList()?
...to store the elements of the list. Arrays cannot be extended once they are allocated so List<T> will use an over-sized array to store the elements of the list. When the List<T> grows beyond the size the underlying array a new array has to be allocated and the contents of the old array ha...
What are some better ways to avoid the do-while(0); hack in C++?
... r1, r2; // , ...;
if(error_ok != (result = computation1(&r1))) // Allocates local resources
goto cleanup;
if(error_ok != (result = computation2(&r2))) // Allocates local resources
goto cleanup;
// ...
// Commit code: all operations succeeded
*r = compute...
Adding values to a C# array
...might be concerned about performance.
The most efficient method is likely allocating a new array and then using Array.Copy or Array.CopyTo. This is not hard if you just want to add an item to the end of the list:
public static T[] Add<T>(this T[] target, T item)
{
if (target == null)
...
What XML parser should I use in C++? [closed]
...is painful for writing XML. It requires you to do a lot of explicit memory allocation of string names in order to build its DOM. It does provide a kind of string buffer, but that still requires a lot of explicit work on your end. It's certainly functional, but it's a pain to use.
It uses the MIT lic...
Creating an instance of class
...
Allocates some dynamic memory from the free store, and creates an object in that memory using its default constructor. You never delete it, so the memory is leaked.
Does exactly the same as 1; in the case of user-defined type...
C libcurl get output into a string
...; len} to the callback function and grows that buffer on each call using realloc().
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
struct string {
char *ptr;
size_t len;
};
void init_string(struct string *s) {
s->len = 0;
s->...
How to use performSelector:withObject:afterDelay: with primitive types in Cocoa?
...st make sure your pointers are still valid after the delay (ie. no objects allocated on stack).
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How do you load custom UITableViewCells from Xib files?
...m cell.
UIViewController *temporaryController = [[UIViewController alloc] initWithNibName:@"BDCustomCell" bundle:nil];
// Grab a pointer to the custom cell.
cell = (BDCustomCell *)temporaryController.view;
[[cell retain] autorelease];
// Release the temporary ...