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Which SQL query is faster? Filter on Join criteria or Where clause?
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Performance-wise, they are the same (and produce the same plans)
Logically, you should make the operation that still has sense if you replace INNER JOIN with a LEFT JOIN.
In your very case this will look like this:
SELECT *
FROM TableA a
LEFT JOIN
TableXRef x
ON x.TableAID = ...
How can I restore the MySQL root user’s full privileges?
I accidentally removed some of the privileges from my MySQL root user, including the ability to alter tables. Is there some way I can restore this user to its original state (with all privileges)?
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Interfaces — What's the point?
...ntract. A set of public methods any implementing class has to have. Technically, the interface only governs syntax, i.e. what methods are there, what arguments they get and what they return. Usually they encapsulate semantics as well, although that only by documentation.
You can then have differen...
How do I format a string using a dictionary in python-3.x?
...3). In many languages, it is known as splat operator. In JavaScript, it's called spread operator. In python, there is no particular name given to this operator.
– abhisekp
Apr 15 '17 at 12:01
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How do I get indices of N maximum values in a NumPy array?
...t been able to find one.
If this solution turns out to be too slow (especially for small n), it may be worth looking at coding something up in Cython.
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Eclipse cannot load SWT libraries
... I get an Unsatisfied Link Error and it will not open. I have recently installed the java JDK and Android SDK, could this be the problem? I followed this tutorial .
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Create a CSV File for a user in PHP
...ord2,record3\n";
die;
etc
Edit: Here's a snippet of code I use to optionally encode CSV fields:
function maybeEncodeCSVField($string) {
if(strpos($string, ',') !== false || strpos($string, '"') !== false || strpos($string, "\n") !== false) {
$string = '"' . str_replace('"', '""', $st...
Receive JSON POST with PHP
...ontents('php://input'), true);
This will save you the hassle of changing all $_POST to something else and allow you to still make normal post requests if you wish to take this line out.
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Why do Java programmers like to name a variable “clazz”? [closed]
...nvention ? I think 'clazz' is not even an English word , has no meaning at all , how can so many programmers name a wrong name coincidentally ?
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Storing time-series data, relational or non?
... description, the actual PK is (Device, Metric, DateTime). (Please don't call it TimeStamp, that means something else, but that is a minor issue.) The uniqueness of the row is identified by:
(Device, Metric, DateTime)
The Id column does nothing, it is totally and completely redundant.
A...