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querySelector and querySelectorAll vs getElementsByClassName and getElementById in JavaScript
I would like to know what exactly is the difference between querySelector and querySelectorAll against getElementsByClassName and getElementById ?
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Code snippet or shortcut to create a constructor in Visual Studio
...a C# project.
So how to make a constructor
Press Ctrl+K and then Ctrl+X
Select Visual C#
Select ctor
Press Tab
Update: You can also right-click in your code where you want the snippet, and select Insert Snippet from the right-click menu
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Solving “Who owns the Zebra” programmatically?
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In Prolog, we can instantiate the domain just by selecting elements from it :) (making mutually-exclusive choices, for efficiency). Using SWI-Prolog,
select([A|As],S):- select(A,S,S1),select(As,S1).
select([],_).
left_of(A,B,C):- append(_,[A,B|_],C).
next_to(A,B,C):- l...
Delete with Join in MySQL
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Since you are selecting multiple tables, The table to delete from is no longer unambiguous. You need to select:
DELETE posts FROM posts
INNER JOIN projects ON projects.project_id = posts.project_id
WHERE projects.client_id = :client_id
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How to pass an array within a query string?
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Form Examples
On a form, multi-valued fields could take the form of a select box set to multiple:
<form>
<select multiple="multiple" name="cars[]">
<option>Volvo</option>
<option>Saab</option>
<option>Mercedes</option...
How I can I lazily read multiple JSON values from a file/stream in Python?
... end_pos = int(re.match('Extra data: line \d+ column \d+ .*\(char (\d+).*\)',
e.args[0]).groups()[0])
json_str = f.read(end_pos)
obj = json.loads(json_str)
start_pos += end_pos
yield obj...
What is :: (double colon) in Python when subscripting sequences?
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TL;DR
This visual example will show you how to a neatly select elements in a NumPy Matrix (2 dimensional array) in a pretty entertaining way (I promise). Step 2 below illustrate the usage of that "double colons" :: in question.
(Caution: this is a NumPy array specific example with...
How to get first record in each group using Linq
...roup element by element.F1
into groups
select groups.OrderBy(p => p.F2).First();
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How to get the max of two values in MySQL?
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Use GREATEST()
E.g.:
SELECT GREATEST(2,1);
Note: Whenever if any single value contains null at that time this function always returns null (Thanks to user @sanghavi7)
s...
How do I query using fields inside the new PostgreSQL JSON datatype?
... a comments below.
The answer to the original question in Postgres 9.3:
SELECT *
FROM json_array_elements(
'[{"name": "Toby", "occupation": "Software Engineer"},
{"name": "Zaphod", "occupation": "Galactic President"} ]'
) AS elem
WHERE elem->>'name' = 'Toby';
Advanced example:
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