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Can table columns with a Foreign Key be NULL?
...enforce the constraint only when the value is not NULL. This can be easily tested with the following example:
CREATE DATABASE t;
USE t;
CREATE TABLE parent (id INT NOT NULL,
PRIMARY KEY (id)
) ENGINE=INNODB;
CREATE TABLE child (id INT NULL,
parent_id INT ...
What is the difference between HashSet and List?
...(1) random access than can grow dynamically (think dynamic array). You can test containment in O(n) time (unless the list is sorted, then you can do a binary search in O(log n) time).
Maybe you can explain with an example in what cases HashSet<T> should be prefered against List<T>
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comparing 2 strings alphabetically for sorting purposes
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Lets look at some test cases - try running the following expressions in your JS console:
"a" < "b"
"aa" < "ab"
"aaa" < "aab"
All return true.
JavaScript compares strings character by character and "a" comes before "b" in the alp...
In Vim, I'd like to go back a word. The opposite of `w`
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use "b" to move back - just tested in vi - works fine.
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String.Empty versus “” [duplicate]
...used in assignments to initialize a string variable to an empty string. To test whether the value of a string is String.Empty, use the IsNullOrEmpty method.
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conversion from string to json object android
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You could just test the first character of the JSON string to see if it is [ or { to know whether it is an array or an object. Then you wouldn't be risking both exceptions, just the pertinent one.
– Jesse Chisholm
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What is the difference between g++ and gcc?
...ng dependencies on math, RTTI, and exception information. Whether a given test case links or fails will depend on the operating system and which C++ features are used by the test case, which again is why all of that knowledge is built into the g++ driver instead of being left up to the user to figu...
jQuery clone() not cloning event bindings, even with on()
...y events for use in mobile web applications. They work great and have been tested. However, I have run into a small problem which I am having trouble understanding.
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Easy way to write contents of a Java InputStream to an OutputStream
... If you're already using the Guava library, Andrejs has recommended the ByteStreams class below. Similar to what IOUtils does, but avoids adding Commons IO to your project.
– Jim Tough
Sep 19 '14 at 12:40
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Is there StartsWith or Contains in t sql with variables?
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I would recommend to test the LIKE 'x%' method mentioned below. In some cases it is much faster
– Tony Sepia
Jun 24 at 21:04
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