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Postgres unique constraint vs index
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Let's check uniqueness, just in case.
test=# insert into master values (0, 0);
INSERT 0 1
test=# insert into master values (0, 1);
ERROR: duplicate key value violates unique constraint "master_con_id_key"
DETAIL: Key (con_id)=(0) already exists.
test=# insert into master values (1, 0);
ERROR: ...
XPath: How to select nodes which have no attributes?
...ath, how to select nodes which have no attributes (where attribute count = 0)?
3 Answers
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DbArithmeticExpression arguments must have a numeric common type
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edited Dec 14 '17 at 11:03
community wiki
7 r...
What does %5B and %5D in POST requests stand for?
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As per this answer over here: str='foo%20%5B12%5D' encodes foo [12]:
%20 is space
%5B is '['
and %5D is ']'
This is called percent encoding and is used in encoding special characters in the url parameter values.
EDIT By the way as I was reading https://develope...
How to sort an array of associative arrays by value of a given key in PHP?
...'price'];
}
array_multisort($price, SORT_DESC, $inventory);
As of PHP 5.5.0 you can use array_column() instead of that foreach:
$price = array_column($inventory, 'price');
array_multisort($price, SORT_DESC, $inventory);
s...
get list from pandas dataframe column
..._one_arr}\ntype:{type(col_one_arr)}")
Output:
DataFrame:
one two
a 1.0 1
b 2.0 2
c 3.0 3
d NaN 4
column types:
one float64
two int64
dtype: object
col_one_list:
[1.0, 2.0, 3.0, nan]
type:<class 'list'>
col_one_arr:
[ 1. 2. 3. nan]
type:<class 'numpy.ndarray...
How do I restore a missing IIS Express SSL Certificate?
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answered Nov 18 '13 at 13:08
Chris SimmonsChris Simmons
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How to add multi line comments in makefiles
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answered Dec 20 '10 at 20:10
Eric MelskiEric Melski
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Test if a command outputs an empty string
...r success, non-zero for failure). For example:
files=$(ls -A)
if [[ $? != 0 ]]; then
echo "Command failed."
elif [[ $files ]]; then
echo "Files found."
else
echo "No files found."
fi
More info here.
share
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How do I convert a Java 8 IntStream to a List?
...il Bourque
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answered May 15 '14 at 9:48
Ian RobertsIan Roberts
112k151...