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Can a foreign key be NULL and/or duplicate?
...from a FK without adding a further constraint on the field. So you have an order table and the order details table for instance. If the customer orders ten items at one time, he has one order and ten order detail records that contain the same orderID as the FK.
...
How to list all Git tags?
...tags?", for Git 2.0+)
git tag --sort=<type>
Sort in a specific order.
Supported type is:
"refname" (lexicographic order),
"version:refname" or "v:refname" (tag names are treated as versions).
Prepend "-" to reverse sort order.
That lists both:
annotated tags:...
Java: Get first item from a collection
...urn the first thing you put in the collection, and may only make sense for ordered collections. Maybe that is why there isn't a get(item) call, since the order isn't necessarily preserved.
While it might seem a bit wasteful, it might not be as bad as you think. The Iterator really just contains i...
Sorting an array of objects by property values
...
Sort homes by price in ascending order:
homes.sort(function(a, b) {
return parseFloat(a.price) - parseFloat(b.price);
});
Or after ES6 version:
homes.sort((a, b) => parseFloat(a.price) - parseFloat(b.price));
Some documentation can be found here...
RESTful Alternatives to DELETE Request Body
... to delete but either it failed or they changed their minds. Reversing the order of the calls would also allow DELETEs to occur without a reason — provision of a reason would then be considered merely as annotation. It is for both of these reasons that I would recommend using option 2 from the abo...
Guava: Why is there no Lists.filter() function?
...
You can use Iterables.filter, which will definitely maintain ordering.
Note that by constructing a new list, you'll be copying the elements (just references, of course) - so it won't be a live view onto the original list. Creating a view would be pretty tricky - consider this situatio...
SQL Server: Difference between PARTITION BY and GROUP BY
... group by modifies the entire query, like:
select customerId, count(*) as orderCount
from Orders
group by customerId
But partition by just works on a window function, like row_number:
select row_number() over (partition by customerId order by orderId)
as OrderNumberForThisCustomer
from Order...
JavaScript regex multiline flag doesn't work
... issues, it is highly recommended to use the *? quantifier instead of * in order to avoid greediness. This will avoid catching the last <h1> of the document: that's probably not what you want and that's not efficient as the regexp will continue to look for <h1> until the end of the strin...
How to Set AllowOverride all
...
<Directory />
Options FollowSymLinks
AllowOverride All
Order allow,deny
Allow from all
</Directory>
Then restart your local server.
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How unique is UUID?
...ely generate a batch of 16,384 UUIDs within the span of a single "tick" in order to overflow the sequence number. I have seen this happen with an implementation that relied, naively, on a clock source that (1) had μs-level granularity, and (2) was not guaranteed to be monotonic (system clocks are ...