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SQL how to increase or decrease one for a int column in one command
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To answer the first:
UPDATE Orders SET Quantity = Quantity + 1 WHERE ...
To answer the second:
There are several ways to do this. Since you did not specify a database, I will assume MySQL.
INSERT INTO table SET x=1, y=2 ON DUPLICATE KEY UPDATE x=x+1, y=y+2
REPLACE INTO table SET ...
delete_all vs destroy_all?
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edited May 23 '17 at 12:26
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answered Jul 14 '11 at 18:36
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Get the first element of each tuple in a list in Python [duplicate]
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196
Use a list comprehension:
res_list = [x[0] for x in rows]
Below is a demonstration:
>&g...
How do I convert a pandas Series or index to a Numpy array? [duplicate]
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To get a NumPy array, you should use the values attribute:
In [1]: df = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6]}, index=['a', 'b', 'c']); df
A B
a 1 4
b 2 5
c 3 6
In [2]: df.index.values
Out[2]: array(['a', 'b', 'c'], dtype=object)
This accesses how the data is already ...
Select count(*) from multiple tables
How can I select count(*) from two different tables (call them tab1 and tab2 ) having as result:
18 Answers
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using awk with column value conditions
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132
If you're looking for a particular string, put quotes around it:
awk '$1 == "findtext" {print...
How to clone git repository with specific revision/changeset?
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15 Answers
15
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How to cast int to enum in C++?
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int i = 1;
Test val = static_cast<Test>(i);
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How to undo a git pull?
...plicit than the other answer:
git pull
whoops?
git reset --keep HEAD@{1}
Versions of git older than 1.7.1 do not have --keep. If you use such version, you could use --hard - but that is a dangerous operation because it loses any local changes.
To the commenter
ORIG_HEAD is previous sta...
What should main() return in C and C++?
...() — and why? And how about the arguments?
If int main() then return 1 or return 0 ?
17 Answers
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