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MySQL select one column DISTINCT, with corresponding other columns
...terminate.". In practice I've successfully used this kind of queries with ORDER BY clause, for instance you could add ORDER BY id ASC/DESC and MySQL would return consistent results every time you would execute the query. But i would be sure whether anyone should use undocumented features in product...
Converting a list to a set changes element order
Recently I noticed that when I am converting a list to set the order of elements is changed and is sorted by character.
...
Why is the order in dictionaries and sets arbitrary?
...tand how looping over a dictionary or set in python is done by 'arbitrary' order.
6 Answers
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Java Class that implements Map and keeps insertion order?
...uggest a LinkedHashMap or a TreeMap. A LinkedHashMap keeps the keys in the order they were inserted, while a TreeMap is kept sorted via a Comparator or the natural Comparable ordering of the elements.
Since it doesn't have to keep the elements sorted, LinkedHashMap should be faster for most cases; ...
What's the difference between RANK() and DENSE_RANK() functions in oracle?
...
RANK gives you the ranking within your ordered partition. Ties are assigned the same rank, with the next ranking(s) skipped. So, if you have 3 items at rank 2, the next rank listed would be ranked 5.
DENSE_RANK again gives you the ranking within your ordered part...
What is a higher kinded type in Scala?
...morphic instantiations).
In the context of abstraction/polymorphism, first-order refers to "single use" of abstraction: you abstract over a type once, but that type itself cannot abstract over anything. Java 5 generics are first-order.
The first-order interpretation of the above characterizations of...
How do I sort one vector based on values of another
I have a vector x, that I would like to sort based on the order of values in vector y. The two vectors are not of the same length.
...
Ordering by specific field value first
...e sorting for all possible values:
SELECT id, name, priority
FROM mytable
ORDER BY FIELD(name, "core", "board", "other")
If you only care that "core" is first and the other values don't matter:
SELECT id, name, priority
FROM mytable
ORDER BY FIELD(name, "core") DESC
If you want to sort by "cor...
Select first row in each GROUP BY group?
...OW_NUMBER() OVER(PARTITION BY p.customer
ORDER BY p.total DESC) AS rk
FROM PURCHASES p)
SELECT s.*
FROM summary s
WHERE s.rk = 1
Supported by any database:
But you need to add logic to break ties:
SELECT MIN(x.id), -- change to MAX if you want the hi...
How to find third or nth maximum salary from salary table?
...(
SELECT EmpID, EmpName, EmpSalary,
RN = ROW_NUMBER() OVER (ORDER BY EmpSalary DESC)
FROM dbo.Salary
)
SELECT EmpID, EmpName, EmpSalary
FROM CTE
WHERE RN = @NthRow
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