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How to change the foreign key referential action? (behavior)
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Old question but adding answer so that one can get help
Its two step process:
Suppose, a table1 has a foreign key with column name fk_table2_id, with constraint name fk_name and table2 is referred table with key t2 (something like below in my diagram).
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How can I break up this long line in Python?
... is to join string literals together implicitly by making them adjacent to one another:
("This is the first line of my text, "
"which will be joined to a second.")
Or with line ending continuations, which is a little more fragile, as this works:
"This is the first line of my text, " \
"which wil...
What does the “map” method do in Ruby?
I'm new to programming. Can someone explain what .map would do in:
7 Answers
7
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Elastic search, multiple indexes vs one index and types for different data sets?
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number of shards can be customized per solution you select. You may have one index with 15 primary shards, or split it to 3 indexes for 5 shards - performance perspective won't change (assuming data are distributed equally)
think about data usage. Ie. if you use kibana to visualize, it's easier to...
Factors in R: more than an annoyance?
One of the basic data types in R is factors. In my experience factors are basically a pain and I never use them. I always convert to characters. I feel oddly like I'm missing something.
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How do I check if there are duplicates in a flat list?
For example, given the list ['one', 'two', 'one'] , the algorithm should return True , whereas given ['one', 'two', 'three'] it should return False .
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What is the difference between a thread and a fiber?
.../etc.). This means that for threads, data integrity is a big issue because one thread may be stopped in the middle of updating a chunk of data, leaving the integrity of the data in a bad or incomplete state. This also means that the operating system can take advantage of multiple CPUs and CPU cores ...
Python memoising/deferred lookup property decorator
Recently I've gone through an existing code base containing many classes where instance attributes reflect values stored in a database. I've refactored a lot of these attributes to have their database lookups be deferred, ie. not be initialised in the constructor but only upon first read. These attr...
Scala: Abstract types vs generics
... can abstract over them.
And what we get conceptually is that we can model one in terms of the other. At least in principle, we can express every sort of parameterization as a form of object-oriented abstraction. So in a sense you could say Scala is a more orthogonal and complete language.
Why?
Wh...
What is “assert” in JavaScript?
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There is no assert in JavaScript (yet; there's talk of adding one, but it's at an early stage). Perhaps you're using some library that provides one. The usual meaning is to throw an error if the expression passed into the function is false; this is part of the general concept of asserti...