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what is reverse() in Django
...d returns the actual url /foo/.
This means that you refer to the url only by its name attribute - if you want to change the url itself or the view it refers to you can do this by editing one place only - urls.py.
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'IF' in 'SELECT' statement - choose output value based on column values
...outh America'
ELSE 'Europe' END AS Continent
FROM Suppliers
ORDER BY CompanyName;
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Postgres: Distinct but only for one column
... to order:
select distinct on (name)
name, col1, col2
from names
order by name, col1
Will return the first row when ordered by col1.
distinct on:
SELECT DISTINCT ON ( expression [, ...] ) keeps only the first row of each set of rows where the given expressions evaluate to equal. The DISTINCT O...
What is the (best) way to manage permissions for Docker shared volumes?
...ther than data containers.
I believe the canonical way to solve this is by using data-only containers. With this approach, all access to the volume data is via containers that use -volumes-from the data container, so the host uid/gid doesn't matter.
For example, one use case given in the documen...
How to convert a List into a comma separated string without iterating List explicitly [dupli
...eplace("]", "")
.replace(", ", ",");
// CSV format surrounded by single quote
// Useful for SQL IN QUERY
String csvWithQuote = ids.toString().replace("[", "'").replace("]", "'")
.replace(", ", "','");
...
.NET unique object identifier
...
A book on .NET by a highly respected author states that RuntimeHelpers.GetHashCode() will produce a code that is unique within an AppDomain, and that Microsoft could have named the method GetUniqueObjectID. This is simply wrong. In testin...
jQuery Multiple ID selectors
... imageUploader: {
brandingHtml: "Powered by \u003ca href=\"https://imgur.com/\"\u003e\u003csvg class=\"svg-icon\" width=\"50\" height=\"18\" viewBox=\"0 0 50 18\" fill=\"none\" xmlns=\"http://www.w3.org/2000/svg\"\u003e\u003cpath d=\"M46.1709 9.17788C46.1709 8.26454...
MySQL, better to insert NULL or empty string?
...
By using NULL you can distinguish between "put no data" and "put empty data".
Some more differences:
A LENGTH of NULL is NULL, a LENGTH of an empty string is 0.
NULLs are sorted before the empty strings.
COUNT(message) wil...
Why would one use nested classes in C++?
...anything exposed is part of the public API and must be maintained forever. By making the class private, I not only hide the implementation I am also saying this is mine and I may change it at any time so you can not use it.
Look at std::list or std::map they all contain hidden classes (or do they?)...
Why can a function modify some arguments as perceived by the caller, but not others?
...unction and outside it refer to the same value, both see the modification. By contrast, the n inside the function and outside it refer to different values after n was reassigned inside the function.
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