大约有 13,000 项符合查询结果（耗时：0.0267秒） [XML]
Rails find record with zero has_many records associated [duplicate]
..._joins(:photos).where(photos: {id: nil})
which will result in SQL like:
SELECT cities.*
FROM cities LEFT OUTER JOIN photos ON photos.city_id = city.id
WHERE photos.id IS NULL
Using includes:
City.includes(:photos).where(photos: {id: nil})
will have the same result, but will result in much ug...
List of ANSI color escape sequences
...
The ANSI escape sequences you're looking for are the Select Graphic Rendition subset. All of these have the form
\033[XXXm
where XXX is a series of semicolon-separated parameters.
To say, make text red, bold, and underlined (we'll discuss many other options below) in C you mig...
Get attribute name value of
... that you were able to add an ID attribute to your element and use that to select it.
With that in mind, here are two pieces of code. First, the code given to you in the Accepted Answer:
$("#ID").attr("name");
And second, the Vanilla JS version of it:
document.getElementById('ID').getAttribute(...
Error to install Nokogiri on OSX 10.9 Maverick?
...r navigating the animated GIFs here, all that I had to do was simply xcode-select --install and the gem install nokogiri worked fine.
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When and why are database joins expensive?
...s back to mitigating the size of the working set. Joins involving properly selected keys with correctly set up indexes are cheap, not expensive, because they allow significant pruning of the result before the rows are materialised.
Materialising the result involves bulk disk reads which are the mo...
How to find the most recent file in a directory using .NET, and without looping?
...ry.GetFiles()
orderby f.LastWriteTime descending
select f).First();
// or...
var myFile = directory.GetFiles()
.OrderByDescending(f => f.LastWriteTime)
.First();
share...
How to resolve : Can not find the tag library descriptor for “http://java.sun.com/jsp/jstl/core” [du
...ting a target server for my project.
i.e. right-click on your project and select 'Properties' -> 'Targeted Runtimes' and select the server you going to run your web app on (Tomcat 6 or 7).
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Dismiss keyboard by touching background of UITableView
...reRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(hideKeyboard)];
[self.tableView addGestureRecognizer:gestureRecognizer];
And the hideKeyboard method might look like this:
- (void) hideKeyboard {
[textField1 resignFirstResponder];
[textField2 resignFirst...
Foreign Key to non-primary key
...int, with a scalar function checking the presence of the key:
IF EXISTS (SELECT * FROM sys.check_constraints WHERE object_id = OBJECT_ID(N'[dbo].[Check_RM_ApertureIDisValid_T_ZO_REM_AP_Raum_Reinigung]') AND parent_object_id = OBJECT_ID(N'[dbo].[T_ZO_REM_AP_Raum_Reinigung]'))
ALTER TABLE dbo.T_ZO_R...
What Java ORM do you prefer, and why? [closed]
...ay give jOOQ a try. You'll love it! :-)
Check out this example SQL:
// Select authors with books that are sold out
SELECT *
FROM T_AUTHOR a
WHERE EXISTS (SELECT 1
FROM T_BOOK
WHERE T_BOOK.STATUS = 'SOLD OUT'
AND T_BOOK.AUTHOR_ID ...