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Does MySQL ignore null values on unique constraints?
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Yes, MySQL allows multiple NULLs in a column with a unique constraint.
CREATE TABLE table1 (x INT NULL UNIQUE);
INSERT table1 VALUES (1);
INSERT table1 VALUES (1); -- Duplicate entry '1' for key 'x'
INSERT table1 VALUES (NULL);
INSER...
Unable to load DLL 'SQLite.Interop.dll'
Periodically I am getting the following exception:
41 Answers
41
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Does “untyped” also mean “dynamically typed” in the academic CS world?
...theory". Programming language theory is based on these foundations. And in all these mathematical contexts, "type" has a particular, well-established meaning.
The terminology "dynamic typing" was invented much later -- and it is a contradiction in terms in the face of the common mathematical use of...
Long-held, incorrect programming assumptions [closed]
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For a long time I assumed that everyone else had this super-mastery of all programming concepts (design patterns, the latest new language, computational complexity, lambda expressions, you name it).
Reading blogs, Stack Overflow and programming books always seemed to make me feel that I was beh...
How does autowiring work in Spring?
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First, and most important - all Spring beans are managed - they "live" inside a container, called "application context".
Second, each application has an entry point to that context. Web applications have a Servlet, JSF uses a el-resolver, etc. Also, th...
What's an object file in C?
...t from the compilation phase. It's mostly machine code, but has info that allows a linker to see what symbols are in it as well as symbols it requires in order to work. (For reference, "symbols" are basically names of global objects, functions, etc.)
A linker takes all these object files and comb...
How to prevent Node.js from exiting while waiting for a callback?
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Callback is Not Queued
Node runs until all event queues are empty. A callback is added to an event queue when a call such as
emmiter1.on('this_event',callback).
has executed. This call is part of the code written by th...
How do I parse command line arguments in Bash?
Say, I have a script that gets called with this line:
37 Answers
37
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How does this print “hello world”?
... 6 symbols
apart from letters. With this codification scheme you can have all 26 (one case) english letters and 6 symbols (being space among them).
Algorithm description
The >>= 5 in the for-loop jumps from group to group, then the 5-bits group gets isolated ANDing the number with the mask ...
jQuery access input hidden value
...$(':hidden#foo').val());
alert($('input:hidden[name=zyx]').val());
Those all mean the same thing in this example.
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