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Can I add a UNIQUE constraint to a PostgreSQL table, after it's already created?
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Also documented in the postgres docs (an excellent resource, plus easy to read, too).
ALTER TABLE tablename ADD CONSTRAINT constraintname UNIQUE (columns);
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is of a type that is invalid for use as a key column in an index
... the 900-byte limit for the maximum total size of all index key columns."
Read more at MSDN
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What is the purpose of a self executing function in javascript?
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@AlexanderBird but that already happens in local variables inside functions: function(){ var foo = 3; alert(foo); }; alert(foo); So I still don't get it
– João Pimentel Ferreira
Dec 3 '17 at 19:08
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How to set up a git project to use an external repo submodule?
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You have a project -- call it MyWebApp that already has a github repo
You want to use the jquery repository in your project
You want to pull the jquery repo into your project as a submodule.
Submodules are really, really easy to reference and use. Assuming you already ...
How can I merge two commits into one if I already started rebase?
...ommits into 1, so I followed “squashing commits with rebase” from git ready .
11 Answers
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Where do the Python unit tests go?
... import tests.thisModule
tests.thisModule.runtests
This lets anybody reading your source code know where to look for the test code.
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Spring .properties file: get element as an Array
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+1, just what I needed. Unfortunately reading comma-separated values into a List<String> in the same fashion doesn't seem to work (the list will have just one element).
– Jonik
May 29 '13 at 8:36
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Why is a ConcurrentModificationException thrown and how to debug it
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This exception has nothing to do with threading concurrency, it is caused by the backing store of the iterator being modified. Whether by another thread of not doesn't matter to the iterator. IMHO it is a poorly named exception since it gives an incorrect impress...
Advantages of std::for_each over for loop
...for_each over for loop? To me, std::for_each only seems to hinder the readability of code. Why do then some coding standards recommend its use?
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Difference between one-to-many and many-to-one relationship
...are one-to-many.
Example:
One area can be the habitat of many readers.
One reader can have many subscriptions.
One newspaper can have many subscriptions.
A Many to One relation is the same as one-to-many, but from a different viewpoint.
Many readers live in one area....