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ERROR 1452: Cannot add or update a child row: a foreign key constraint fails
...relationships involve a parent table that holds the
central data values, and a child table with identical values pointing
back to its parent. The FOREIGN KEY clause is specified in the child
table.
It will reject any INSERT or UPDATE operation that attempts to create
a foreign key value...
Does MongoDB's $in clause guarantee order
...the results
{ "$sort": { "weight": 1 } }
])
So that would be the expanded form. What basically happens here is that just as the array of values is passed to $in you also construct a "nested" $cond statement to test the values and assign an appropriate weight. As that "weight" value reflects t...
How can I create a copy of an object in Python?
... you can use the copy.deepcopy() function.
For more details about shallow and deep copying please refer to the other answers to this question and the nice explanation in this answer to a related question.
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Sorting an array of objects by property values
I've got the following objects using AJAX and stored them in an array:
30 Answers
30
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IPC performance: Named Pipe vs Socket
...y? I would prefer to use sockets because they can do two-way communication and are very flexible but will choose speed over flexibility if it is by considerable amount.
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SQLite with encryption/password protection
I'm just learning to use SQLite and I was curious if such is possible:
9 Answers
9
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How to show only next line after the matched one?
Thanks to this command for every line that has 'blah' in it, I get the output of the line that contains 'blah' and the next line that follows in the logfile. It might be a simple one but I can't find a way to omit the line that has 'blah' and only show next line in the output.
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What is causing this error - “Fatal error: Unable to find local grunt”
...ed the old version of grunt first, then I installed the new grunt version, and then I got this error:
13 Answers
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How can you speed up Eclipse?
... Indigo (3.7.2) SR2 loads in 4 seconds, in Kepler SR2 (4.3.2) in 7 seconds and in Luna (4.4.0) in 10 seconds. All are Java EE bundles. Newer versions have more bundled plugins, but still the trend is obvious. (by "same" workspace I mean: same (additionally installed) plugins used, same projects chec...
How to order by with union in SQL?
Is it possible to order when the data is come from many select and union it together? Such as
8 Answers
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