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When to add what indexes in a table in Rails
...B and simply A, so you can design your indexes to be more versatile if you order them correctly. The phone book is indexed on Last Name, First Name, so you can look up people easily by their last name, or a combination of last name and first name. You cannot, however, look them up directly by their ...
jQuery UI Sortable, then write order into a database
I want to use the jQuery UI sortable function to allow users to set an order and then on change, write it to the database and update it. Can someone write an example on how this would be done?
...
Understanding dispatch_async
...asks within a given queue will begin executing using "first in, first out" order. This is in comparison to the main queue (from dispatch_get_main_queue()), which is a serial queue (tasks will begin executing and finish executing in the order in which they are received).
So, if you send 1000 dispatc...
Why does the order of the loops affect performance when iterating over a 2D array?
... x[1][0] etc...
Meaning that you're hitting them all in order. Now look at the 1st version. You're doing:
x[0][0]
x[1][0]
x[2][0]
x[0][1]
...
How to get the sizes of the tables of a MySQL database?
...x_length) / 1024 / 1024), 2) `Size in MB`
FROM information_schema.TABLES
ORDER BY (data_length + index_length) DESC;
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Should sorting logic be placed in the model, the view, or the controller? [closed]
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Who controls the sort order?
(From Wikipedia)
1) Natural order within the data itself:
The order is part of the Model, so it should go there. A raw pull of "all data" would return the data in the sorted order, and there is no interface to cho...
Why does this Java program terminate despite that apparently it shouldn't (and didn't)?
...ur object is not safely published those 4 write operations can be freely reordered by the compiler / JVM.
So from the perspective of the reading thread, it is a legal execution to read x with its new value but y with its default value of 0 for example. By the time you reach the println statement (w...
MVC Razor view nested foreach's model
...el=>model.Theme[themeIndex].Products[productIndex].name)
@for(var orderIndex=0; orderIndex < Model.Theme[themeIndex].Products[productIndex].Orders; orderIndex++)
{
@Html.TextBoxFor(model => model.Theme[themeIndex].Products[productIndex].Orders[orderIndex].Quantity)
...
Dynamically select data frame columns using $ and a character value
...the second is a data.frame
mtcars[[var]]
mtcars[var]
You can perform the ordering without loops, using do.call to construct the call to order. Here is a reproducible example below:
# set seed for reproducibility
set.seed(123)
df <- data.frame( col1 = sample(5,10,repl=T) , col2 = sample(5,10,r...
For-each over an array in JavaScript
...k (not used above). The callback is called for each entry in the array, in order, skipping non-existent entries in sparse arrays. Although I only used one argument above, the callback is called with three: The value of each entry, the index of that entry, and a reference to the array you're iteratin...