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Swift: Pass array by reference?
...nt to pass my Swift Array account.chats to chatsViewController.chats by reference (so that when I add a chat to account.chats , chatsViewController.chats still points to account.chats ). I.e., I don't want Swift to separate the two arrays when the length of account.chats changes.
...
Simultaneously merge multiple data.frames in a list
...concise syntax:
library(tidyverse)
list(x, y, z) %>% reduce(left_join, by = "i")
# A tibble: 3 x 4
# i j k l
# <chr> <int> <int> <int>
# 1 a 1 NA 9
# 2 b 2 4 NA
# 3 c 3 5 7
You can also perform other joins, such as a...
Retrieving the last record in each group - MySQL
...ies:
WITH 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...
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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What is stability in sorting algorithms and why is it important?
...appear in the input array to be sorted. Some sorting algorithms are stable by nature like Insertion sort, Merge Sort, Bubble Sort, etc. And some sorting algorithms are not, like Heap Sort, Quick Sort, etc.
Background: a "stable" sorting algorithm keeps the items with the same sorting key in order....
How do I sort a dictionary by value?
...s(), key=operator.itemgetter(1))
sorted_x will be a list of tuples sorted by the second element in each tuple. dict(sorted_x) == x.
And for those wishing to sort on keys instead of values:
import operator
x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}
sorted_x = sorted(x.items(), key=operator.itemgetter(0))
I...
Implement paging (skip / take) functionality with this query
...it is very very easy
SELECT col1, col2, ...
FROM ...
WHERE ...
ORDER BY -- this is a MUST there must be ORDER BY statement
-- the paging comes here
OFFSET 10 ROWS -- skip 10 rows
FETCH NEXT 10 ROWS ONLY; -- take 10 rows
If we want to skip ORDER BY we can use
SELECT col1, col2, ......
ng-repeat :filter by single field
...ter page. Use an object, and set the color in the color property:
Search by color: <input type="text" ng-model="search.color">
<div ng-repeat="product in products | filter:search">
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Sorting an array of objects in Ruby by object attribute?
I have an array of objects in Ruby on Rails. I want to sort the array by an attribute of the object. Is it possible?
9 Answ...
Why does MYSQL higher LIMIT offset slow the query down?
...MIT offset with SELECT, the slower the query becomes, when using ORDER BY *primary_key*
6 Answers
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