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Retrieving the last record in each group - MySQL
...TH ranked_messages AS (
SELECT m.*, ROW_NUMBER() OVER (PARTITION BY name ORDER BY id DESC) AS rn
FROM messages AS m
)
SELECT * FROM ranked_messages WHERE rn = 1;
Below is the original answer I wrote for this question in 2009:
I write the solution this way:
SELECT m1.*
FROM messages m1 LEFT...
原子vector的一种实现源码(atomic-vector) - C/C++ - 清泛网 - 专注C/C++及内核技术
...cting\n",
typeName(), this);
delete m_next.load(std::memory_order_relaxed);
}
template<typename Value>
void AtomicVector<Value>::ensureSize(size_t size) {
FTRACE(2, "{}::ensureSize({}), m_size = {}\n",
typeName(), size, m_size);
if (m_size >= size) return;
au...
MySQL, update multiple tables with one query
...
Take the case of two tables, Books and Orders. In case, we increase the number of books in a particular order with Order.ID = 1002 in Orders table then we also need to reduce that the total number of books available in our stock by the same number in Books table.
...
Is main() really start of a C++ program?
... don't have full control prior to main, you don't have full control on the order in which the static blocks get initialized.
After main, your code is conceptually "fully in control" of the program, in the sense that you can both specify the instructions to be performed and the order in which to per...
What is the order of precedence for CSS?
...
There are several rules ( applied in this order ) :
inline css ( html style attribute ) overrides css rules in style tag and css file
a more specific selector takes precedence over a less specific one
rules that appear later in the code override earlier rules if bo...
What is the difference between Collection and List in Java?
...5th element in this collection" isn't defined, because there is no defined order.
There are other specialized Collections as well, for example a Set which adds the feature that it will never contain the same element twice.
...
Define: What is a HashSet?
...lculated from the hashcode of the object. Take a look here
HashSet is an unordered collection containing unique elements. It has the standard collection operations Add, Remove, Contains, but since it uses a hash-based implementation, these operations are O(1). (As opposed to List for example, which ...
Is it possible to import a whole directory in sass using @import?
...in another answer "If you import a directory, how can you determine import order? There's no way that doesn't introduce some new level of complexity."
Some would argue that organizing your files into directories can REDUCE complexity.
My organization's project is a rather complex app. There are ...
How to sort Map values by key in Java?
...t(key);
// do something
}
This will iterate across the map in natural order of the keys.
Longer answer
Technically, you can use anything that implements SortedMap, but except for rare cases this amounts to TreeMap, just as using a Map implementation typically amounts to HashMap.
For case...
Best way of invoking getter by reflection
...
Is there a way to invoke the methods in the order in which the fields are listed in the Java file?
– LifeAndHope
Jun 21 '15 at 19:37
...