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Is there any performance gain in indexing a boolean field?
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It depends on the actual queries and the selectivity of the index/query combination.
Case A: condition WHERE isok = 1 and nothing else there:
SELECT *
FROM tableX
WHERE isok = 1
If the index is selective enough (say you have 1M rows and only 1k have isok = 1), ...
Rename a class in Xcode: Refactor… is grayed out (disabled). Why?
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Select the class's symbol in its header file - i.e. the bit just after @interface. Then the refactoring stuff should be enabled.
share
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PHP MySQL Google Chart JSON - Complete Example
... else
{
//echo ("Connect Successfully");
}
$query = "SELECT Date_time, Tempout FROM alarm_value"; // select column
$aresult = $con->query($query);
?>
<!DOCTYPE html>
<html>
<head>
<title>Massive Electronics</title>
<script ty...
How to correct indentation in IntelliJ
...ode → Auto-Indent Lines (default Ctrl + Alt + I) for the current line or selection.
You can customise the settings for how code is auto-formatted under File → Settings → Editor → Code Style.
To ensure comments are also indented to the same level as the code, you can simply do as follows:...
CSS Child vs Descendant selectors
I am a bit confused between these 2 selectors.
8 Answers
8
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java.sql.SQLException: - ORA-01000: maximum open cursors exceeded
... a query, specifically the position where a reader is in a ResultSet. Each SELECT statement has a cursor, and PL/SQL stored procedures can open and use as many cursors as they require. You can find out more about cursors on Orafaq.
A database instance typically serves several different schemas, man...
Moving Files into a Real Folder in Xcode
... Xcode should now be red (that's OK!).
From the Identity and Type manager, select the Group in Xcode that you want to relocate, then click the folder icon from the info pane:
In the Finder selection dialog, locate the equivalent new folder you created for this group in step 2. All the files insid...
Copy/duplicate database without using mysqldump
...the references, you can run the following to copy the data:
INSERT INTO x SELECT * FROM other_db.y;
If you're using MyISAM, you're better off to copy the table files; it'll be much faster. You should be able to do the same if you're using INNODB with per table table spaces.
If you do end up doin...
Using IntelliJ to amend git commit message
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Amend is supported: invoke "Commit Changes" and select the checkbox "Amend commit" in the Commit Dialog. Then press "Commit" button, and the commit will be amended to the previous one.
However, the support is limited:
you can't see the details of the commit being amend...
Inefficient jQuery usage warnings in PHPStorm IDE
...o find a solution thanks to Scott Kosman here.
Basically the answer is to select IDs individually and then use .find(...) for anything below. So taking your example:
$("#property [data-role='content'] .container");
Changing it to this makes PhpStorm happy and can evidently be more than twice as ...