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MySQL foreign key constraints, cascade delete
...#2 (blue):
DELETE FROM categories WHERE (id = 2);
the DBMS will look at all the tables which have a foreign key pointing at the 'categories' table, and delete the records where the matching id is 2. Since we only defined the foreign key relationship in products_categories, you end up with this ta...
“CAUTION: provisional headers are shown” in Chrome debugger
...ield to find the event related to your resource (use parts of the URL).
Finally, click on the event and see if the info shown tells you something.
For Older Versions of chrome
Type chrome://net-internals in the address bar and hit enter.
Open the page that is showing problems.
Go back to net-int...
How can I pad a value with leading zeros?
... If performance is a concern for you, don't use this solution!
Potentially outdated: ECMAScript 2017 includes String.prototype.padStart and Number.prototype.toLocaleString is there since ECMAScript 3.1. Example:
var n=-0.1;
n.toLocaleString('en', {minimumIntegerDigits:4,minimumFractionDigits:2...
What is the difference between related SQLite data-types like INT, INTEGER, SMALLINT and TINYINT?
When creating a table in SQLite3, I get confused when confronted with all the possible datatypes which imply similar contents, so could anyone tell me the difference between the following data-types?
...
GitHub: How to make a fork of public repository private?
...plicate the repo as others said (details here):
Create a new repo (let's call it private-repo) via the Github UI. Then:
git clone --bare https://github.com/exampleuser/public-repo.git
cd public-repo.git
git push --mirror https://github.com/yourname/private-repo.git
cd ..
rm -rf public-repo.git
...
Efficient way to return a std::vector in c++
...urn value (by value) is: instead of 'been moved', the return value in the callee is created on the caller's stack, so all operations in the callee are in-place, there is nothing to move in RVO. Is that correct?
– r0ng
Sep 5 '18 at 5:59
...
Image fingerprint to compare similarity of many images
...d approach for improved comparison quality
A luminosity histogram (especially one that is separated into RGB components) is a reasonable fingerprint for an image - and can be implemented quite efficiently. Subtracting one histogram from another will produce a new historgram which you can process t...
What are the pros and cons of the leading Java HTML parsers? [closed]
...
General
Almost all known HTML parsers implements the W3C DOM API (part of the JAXP API, Java API for XML processing) and gives you a org.w3c.dom.Document back which is ready for direct use by JAXP API. The major differences are usually to b...
Is there a “null coalescing” operator in JavaScript?
...an results in false, the assignment will use the second operand. Beware of all the cases below:
alert(Boolean(null)); // false
alert(Boolean(undefined)); // false
alert(Boolean(0)); // false
alert(Boolean("")); // false
alert(Boolean("false")); // true -- gotcha! :)
This means:
var whatIWant = n...
Django auto_now and auto_now_add
... change between every release. (Which I believe is the impetus behind the call to have them removed altogether).
The fact that they only work on DateField, DateTimeField, and TimeField, and by using this technique you are able to automatically populate any field type every time an item is saved.
Use...