大约有 12,000 项符合查询结果（耗时：0.0398秒） [XML]
Best way to select random rows PostgreSQL
... few) gaps.
Obviously no or few write operations.
Your ID column has to be indexed! A primary key serves nicely.
The query below does not need a sequential scan of the big table, only an index scan.
First, get estimates for the main query:
SELECT count(*) AS ct -- optional
, mi...
When to use Common Table Expression (CTE)
...a simple example of limitations with regular select, derived or temp table queries to make the case of CTE? Any simple examples would be highly appreciated.
...
Possibility of duplicate Mongo ObjectId's being generated in two different collections?
... }
> db.foo.insert({_id: 'abc', data:'xyz'})
E11000 duplicate key error index: test.foo.$_id_ dup key: { : "abc" }
So, absolutely don't rely on _id's being unique across collections, and since you don't control the ObjectId generation function, don't rely on it.
It's possible to create somet...
MVC 3: How to render a view without its layout page when loaded via ajax?
...ws/Shared/_Layout.cshtml";
}
and in the controller:
public ActionResult Index()
{
return View();
}
share
|
improve this answer
|
follow
|
...
How do I print out the contents of an object in Rails for easy debugging?
...onView::Helpers::DebugHelper
#app/view/controllers/post_controller.rb
def index
@posts = Post.all
end
#app/view/posts/index.html.erb
<%= debug(@posts) %>
#start your server
rails -s
results (in browser)
- !ruby/object:Post
raw_attributes:
id: 2
title: My Second Post
body: ...
How to clear all the jobs from Sidekiq?
I am using sidekiq for background tasks in Rails application. Now the numbers of jobs becomes more, so I want to clear all the jobs. I tried the following command in console
...
How do I exit from the text window in Git?
...vim, you can press i to start entering text and save by pressing esc and :wq and enter, this will commit with the message you typed. In your current state, to just come out without committing, you can do :q instead of the :wq as mentioned above.
Alternatively, you can just do git commit -m '<mes...
Injecting $state (ui-router) into $http interceptor causes circular dependency
... get a reference to the $state service.
var interceptor = ['$location', '$q', '$injector', function($location, $q, $injector) {
function success(response) {
return response;
}
function error(response) {
if(response.status === 401) {
$injector.get('$state')....
How to write UPDATE SQL with Table alias in SQL Server 2008?
I have a very basic UPDATE SQL -
2 Answers
2
...
Create a dictionary with list comprehension
...;
Notice the use of enumerate here to get a list of alphabets and their indexes in the list and swapping the alphabets and indices to generate the key value pair for dictionary
Hope it gives a good idea of dictionary comp to you and encourages you to use it more often to make your code compact
...