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Can I add a UNIQUE constraint to a PostgreSQL table, after it's already created?
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I needed an answer to this very question and started googling for the docs. Instead of the Postgres documentation, I ran into this topic at StackOverflow. So although it's a good think to reference the official docs, it's also very good to give the answer for future...
How can I extract a good quality JPEG image from a video file with ffmpeg?
Currently I am using this command to extract the images:
2 Answers
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Implement paging (skip / take) functionality with this query
I have been trying to understand a little bit about how to implement custom paging in SQL, for instance reading articles like this one .
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What does the “@” symbol do in Powershell?
... in PowerShell to initialise arrays. What exactly does the @ symbol denote and where can I read more about it?
5 Answers
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Haskell Type vs Data Constructor
...m learning Haskell from learnyouahaskell.com . I am having trouble understanding type constructors and data constructors. For example, I don't really understand the difference between this:
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Remove a file from a Git repository without deleting it from the local filesystem
...ial commit contained some log files. I've added *log to my .gitignore , and now I want to remove the log files from my repository.
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Open files in 'rt' and 'wt' modes
Several times here on SO I've seen people using rt and wt modes for reading and writing files.
4 Answers
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Explain the use of a bit vector for determining if all characters are unique
...ay be a little bit faster, because operations with bits are very low level and can be executed as-is by CPU. BitVector allows writing a little bit less cryptic code instead plus it can store more flags.
For future reference: bit vector is also known as bitSet or bitArray. Here are some links to thi...
Debug code-first Entity Framework migration codes
I'm using Entity Framework code first in my website and I'm just wondering if there is any way to debug the migration codes. You know, like setting breakpoints and stuff like this.
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Use a LIKE statement on SQL Server XML Datatype
...varchar(100)') LIKE 'XYZ%'
The .value method gives you the actual value, and you can define that to be returned as a VARCHAR(), which you can then check with a LIKE statement.
Mind you, this isn't going to be awfully fast. So if you have certain fields in your XML that you need to inspect a lot, ...