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MySQL CONCAT returns NULL if any field contain NULL
I have following data in my table "devices"
6 Answers
6
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How to ignore files which are in repository?
...Git repository, but I want to ignore locally, i.e. I want that file to remain in repository, but force Git to ignore any changes to it.
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PostgreSQL - Rename database
I need to rename the database but when I do in
PGAdmin : ALTER DATABASE "databaseName" RENAME TO "databaseNameOld" it told me that it cannot.
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Creating a new column based on if-elif-else condition
...lse:
val = -1
return val
Then apply it to your dataframe passing in the axis=1 option:
In [1]: df['C'] = df.apply(f, axis=1)
In [2]: df
Out[2]:
A B C
a 2 2 0
b 3 1 1
c 1 3 -1
Of course, this is not vectorized so performance may not be as good when scaled to a large num...
return query based on date
I have a data like this in mongodb
7 Answers
7
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Capturing Ctrl-c in ruby
I was passed a long running legacy ruby program, which has numerous occurrences of
5 Answers
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How do you use window.postMessage across domains?
It seems like the point of window.postMessage is to allow safe communication between windows/frames hosted on different domains, but it doesn't actually seem to allow that in Chrome.
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Does setWidth(int pixels) use dip or px?
Does setWidth(int pixels) use device independent pixel or physical pixel as unit?
For example, does setWidth(100) set the a view's width to 100 dips or 100 pxs?
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Submitting the value of a disabled input field
I want to disable an input field, but when I submit the form it should still pass the value.
4 Answers
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Rails migrations: self.up and self.down versus change
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For many operations rails can guess what is the inverse operation (without problems). For example, in your case what is the reverse operation of add_column to call when you rollback? Of course it's remove_column. What is the inverse of create_table? It's drop_table. So in ...