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How to concatenate strings of a string field in a PostgreSQL 'group by' query?
...in any aggregate expression; otherwise, the order is undefined. So you can now write:
SELECT company_id, string_agg(employee, ', ' ORDER BY employee)
FROM mytable
GROUP BY company_id;
Or indeed:
SELECT string_agg(actor_name, ', ' ORDER BY first_appearance)
PostgreSQL 8.4 or later:
PostgreSQL ...
How to remove a directory from git repository?
...l this delete the directory from the point it was added to repository till now? Or is it just to remove the directory and recommit it to the .git repo?
– alpha_989
Jan 21 '18 at 18:15
...
C++ obtaining milliseconds time on Linux — clock() doesn't seem to work properly
...
For now you can use the Boost Timer and then gracefully migrate to Chrono when it is reviewed/accepted.
– Anonymous
Feb 26 '09 at 13:40
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Clear a terminal screen for real
...
@SDX2000 OK ... I know you specified Ubuntu, and I assumed that these would behave similar on all "modern" terminal emulators. I initially tested on my MAC's terminal and it did not reset there, but it did reset on my Centos Linux.
...
What does “Changes not staged for commit” mean
... may see this error when you have added a new file to your code and you're now trying to commit the code without staging(adding) it.
To overcome this, you may first add the file by using git add (git add your_file_name.py) and then committing the changes (git commit -m "Rename Files" -m "Sample scr...
How to clear the canvas for redrawing
...perimenting with composite operations and drawing images on the canvas I'm now trying to remove images and compositing. How do I do this?
...
Using CSS td width absolute, position
...ning that there is a table width threshold. Problem is sometimes we don't know the overall width before hand. What is the default table width?
– Jake
Feb 8 '13 at 5:51
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NameError: global name 'unicode' is not defined - in Python 3
...t Martijn, I forgot to include : in my code, thanks for the help, it works now.
– TJ1
Nov 9 '13 at 15:13
I like 2to3 t...
Understanding generators in Python
...u do not look into until you understand the basic concept of a generator.
Now you may ask: why use generators? There are a couple of good reasons:
Certain concepts can be described much more succinctly using generators.
Instead of creating a function which returns a list of values, one can write ...
Pandas: drop a level from a multi-level column index?
...
As of Pandas 0.24.0, we can now use DataFrame.droplevel():
cols = pd.MultiIndex.from_tuples([("a", "b"), ("a", "c")])
df = pd.DataFrame([[1,2], [3,4]], columns=cols)
df.droplevel(0, axis=1)
# b c
#0 1 2
#1 3 4
This is very useful if you wan...