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SQL Add foreign key to existing column
... no UserID column in your Employees table. Try adding the column first and then re-run the statement.
ALTER TABLE Employees
ADD CONSTRAINT FK_ActiveDirectories_UserID FOREIGN KEY (UserID)
REFERENCES ActiveDirectories(id);
...
Using a dispatch_once singleton model in Swift
...thread safe, what if that static struct var is a dictionary for multitons, then we have to manually synchronize/queue calls to it for each access, right?
– user3610227
Dec 31 '14 at 0:27
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Storing C++ template function definitions in a .CPP file
...fining the function a() {}) and b.cpp (defining the function b() { a() }), then this will successfully link. If I'm right, then the above quote would seem not to apply for the typical case... am I going wrong somewhere?
– Dan Nissenbaum
Jun 12 '14 at 19:46
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Reshaping data.frame from wide to long format
...tive you can also specify the measure-variables
# all other variables will then be used as id-variables
melt(wide, measure.vars = 3:7)
melt(wide, measure.vars = as.character(1950:1954))
NOTES:
reshape2 is retired. Only changes necessary to keep it on CRAN will be made. (source)
If you want to ...
How to install JSTL? The absolute uri: http://java.sun.com/jstl/core cannot be resolved
...a, etc instead of a barebones servletcontainer such as Tomcat, Jetty, etc, then you don't need to explicitly install JSTL at all. Normal Java EE servers already provide JSTL out the box. In other words, you don't need to add JSTL to pom.xml nor to drop any JAR/TLD files in webapp. Solely the provide...
Why does the order of the loops affect performance when iterating over a 2D array?
...mputing L2 cache size is everything because if all your arrays fit into L2 then computation can be completed without going to main memory.
– Michael Shopsin
Mar 30 '12 at 15:26
4
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Regex Email validation
...er verify they received the email by clicking a link or entering a token.
Then there are throw-away domains, such as Mailinator.com, and such. This doesn't do anything to verify whether an email is from a throwaway domain or not.
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android fragment- How to save states of views in a fragment when another fragment is pushed on top o
...ing fragment via xml layout. Had to change the mCurCheckPosition to static then it works, but feels hacky.
– scottyab
Jul 10 '12 at 11:25
57
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Placing border inside of div and not on its edge
...taining the pseudo element using absolute position relative to the parent. Then you have freedom to have whatever custom background and/or border in the background of your main element.
This approach does not affect placement of the contents of the main element, which is different from using box-si...
INSERT … ON DUPLICATE KEY (do nothing)
...n (it's incremented even if the row is not inserted due to duplicate key), then use INSERT IGNORE.
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