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Postgresql aggregate array
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What I understand you can do something like this:
SELECT p.p_name,
STRING_AGG(Grade.Mark, ',' ORDER BY Grade.Mark) As marks
FROM Student
LEFT JOIN Grade ON Grade.Student_id = Student.Id
GROUP BY Student.Name;
EDIT
I am not sure. B...
Fastest way to extract frames using ffmpeg?
...about 20 times faster. We use fast seeking to go to the desired time index and extract a frame, then call ffmpeg several times for every time index. Note that -accurate_seek is the default
, and make sure you add -ss before the input video -i option.
Note that it's better to use -filter:v -fps=fps=...
SQLAlchemy: print the actual query
...enge here is that SQLAlchemy normally is not tasked with this, as this is handled appropriately by the Python DBAPI, not to mention bypassing bound parameters is probably the most widely exploited security holes in modern web applications. SQLAlchemy has limited ability to do this stringification ...
How to get a enum value from string in C#?
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Before .NET 4.5, you had to do the following, which is more error-prone and throws an exception when an invalid string is passed:
(uint)Enum.Parse(typeof(baseKey), "HKEY_LOCAL_MACHINE")
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Bash script to set up a temporary SSH tunnel
...ly with an ssh 'control socket'. To talk to an already-running SSH process and get it's pid, kill it etc. Use the 'control socket' (-M for master and -S for socket) as follows:
$ ssh -M -S my-ctrl-socket -fnNT -L 50000:localhost:3306 jm@sampledomain.com
$ ssh -S my-ctrl-socket -O check jm@sampledo...
What's the best practice for primary keys in tables?
...signing tables, I've developed a habit of having one column that is unique and that I make the primary key. This is achieved in three ways depending on requirements:
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xcode-select active developer directory error
...en xcode-select developer directory was pointing to /Library/Developer/CommandLineTools, when a full regular Xcode was required (happens when CommandLineTools are installed after Xcode)
Solution:
Install Xcode (get it from https://appstore.com/mac/apple/xcode) if you don't have it yet.
Accept th...
Why check both isset() and !empty()
Is there a difference between isset and !empty . If I do this double boolean check, is it correct this way or redundant? and is there a shorter way to do the same thing?
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Casting to string in JavaScript
...avaScript.
I searched for those three options in the jQuery source code, and they are all in use .
I would like to know if there are any differences between them:
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How can I prevent SQL injection in PHP?
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Use prepared statements and parameterized queries. These are SQL statements that are sent to and parsed by the database server separately from any parameters. This way it is impossible for an attacker to inject malicious SQL.
You basically have two...