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How to select unique records by SQL
..., but also the most limited way:
SELECT DISTINCT word, num
FROM dupes
ORDER BY word, num;
/*
word|num|
----|---|
aaa |100|
bbb |200|
bbb |400|
ccc |300|
ddd |400|
*/
Option 2: GROUP BY
Grouping allows you to add aggregated data, like the min(id), max(id), count(*), etc:
SELECT word, num, ...
Can I concatenate multiple MySQL rows into one field?
...d in their comment, you can also sort the values before imploding it using ORDER BY:
SELECT person_id, GROUP_CONCAT(hobbies ORDER BY hobbies ASC SEPARATOR ', ')
FROM peoples_hobbies
GROUP BY person_id;
As Dag stated in his comment, there is a 1024 byte limit on the result. To solve this, run this q...
Postgresql GROUP_CONCAT equivalent?
...
Note that the syntax also allows you to specify the order of values in the string (or array, using array_agg) e.g. string_agg(some_column, ',' ORDER BY some_column) or even string_agg(surname || ', ' || forename, '; ' ORDER BY surname, forename)
– IMSoP
...
SQlite Getting nearest locations (with latitude and longitude)
... other latitudes, you need to decrease the impact of longitude on the sort order. (Imagine you're close to the north pole... a degree of latitude is still the same as it is anywhere, but a degree of longitude may only be a few feet. This will mean that the sort order is incorrect).
If you are not...
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...
lodash multi-column sortBy descending
...
As of lodash 3.5.0 you can use sortByOrder (renamed orderBy in v4.3.0):
var data = _.sortByOrder(array_of_objects, ['type','name'], [true, false]);
Since version 3.10.0 you can even use standard semantics for ordering (asc, desc):
var data = _.sortByOrder(ar...
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...
Accessing items in an collections.OrderedDict by index
...
If its an OrderedDict() you can easily access the elements by indexing by getting the tuples of (key,value) pairs as follows
>>> import collections
>>> d = collections.OrderedDict()
>>> d['foo'] = 'python'
&...
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.
...
How to find gaps in sequential numbering in mysql?
... Note: This query doesn't work on temporary tables. My problem was the order number I was searching for gaps in is not distinct (the table stores order lines, so the order number they belong to repeats for each line). 1st query: 2812 rows in set (1 min 31.09 sec). Made another table by selecting...