大约有 30,000 项符合查询结果（耗时：0.0160秒） [XML]
selecting unique values from a column
...se the DISTINCT operator in MySQL:
SELECT DISTINCT(Date) AS Date FROM buy ORDER BY Date DESC;
share
|
improve this answer
|
follow
|
...
ORDER BY the IN value list
...s c
join (
values
(1,1),
(3,2),
(2,3),
(4,4)
) as x (id, ordering) on c.id = x.id
order by x.ordering
share
|
improve this answer
|
follow
|...
How can you do paging with NHibernate?
...ed to execute a separate transaction for retrieving the total row count in order to render your pager.
– Kevin Pang
Jan 7 '09 at 0:44
1
...
How to pull a random record using Django's ORM?
...
Using order_by('?') will kill the db server on the second day in production. A better way is something like what is described in Getting a random row from a relational database.
from django.db.models.aggregates import Count
from r...
What is the difference between . (dot) and $ (dollar sign)?
...ns to be chained together without adding parentheses to control evaluation order:
Prelude> head (tail "asdf")
's'
Prelude> head $ tail "asdf"
's'
The compose operator (.) creates a new function without specifying the arguments:
Prelude> let second x = head $ tail x
Prelude> second "...
Show all Elasticsearch aggregation results/buckets and not just 10
...s 10 documents by default. We don't need them.
By default, the buckets are ordered by the doc_count in decreasing order.
Why do I get Fielddata is disabled on text fields by default error?
Because fielddata is disabled on text fields by default. If you have not wxplicitly chosen a field typ...
Java generics type erasure: when and what happens?
...in the caller) to check types. The generic objects themselves are just the raw type; the parameterized type is "erased". So, when you create a new Box<Integer>(), there is no information about the Integer class in the Box object.
Angelika Langer's FAQ is the best reference I've seen for Java ...
Get to UIViewController from UIView?
...API features. Many I have referred to sacrifice good or scalable design in order to provide a concise demonstration of the topic. It took me a long time to realise this and while it makes sense, I find it unfortunate. I think a lot of developers take these pragmatic projects as Apple's guide to best...
Best way to check if object exists in Entity Framework?
...tes.
In short, if you have timestamped raw data coming in, pretty much in order, then using a memory cache might help with the record duplication check.
share
|
improve this answer
|
...
Getting a list of associative array keys
...rticle: Iterates over the enumerable properties of an object, in arbitrary order. If key order is important, you need to do something like pushing them in an array, sorting it, and then using a for() loop to get keys from the sorted array with which to index the original object.
...