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SQL Joins Vs SQL Subqueries (Performance)?
...PECT the first query to be quicker, mainly because you have an equivalence and an explicit JOIN. In my experience IN is a very slow operator, since SQL normally evaluates it as a series of WHERE clauses separated by "OR" (WHERE x=Y OR x=Z OR...).
As with ALL THINGS SQL though, your mileage may va...
Making heatmap from pandas DataFrame
I have a dataframe generated from Python's Pandas package. How can I generate heatmap using DataFrame from pandas package.
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What are the differences between 'call-template' and 'apply-templates' in XSL?
...name="dosomething">.
<xsl:apply-templates> is a little different and in it is the real power of XSLT: It takes any number of XML nodes (whatever you define in the select attribute), iterates them (this is important: apply-templates works like a loop!) and finds matching templates for them:...
Which is more preferable to use: lambda functions or nested functions ('def')?
...efs are just syntactic sugar for an assignment, so the result is the same, and they are a lot more flexible and readable.
lambdas can be used for use once, throw away functions which won't have a name.
However, this use case is very rare. You rarely need to pass around unnamed function objects.
T...
Why doesn't Objective-C support private methods?
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The answer is... well... simple. Simplicity and consistency, in fact.
Objective-C is purely dynamic at the moment of method dispatch. In particular, every method dispatch goes through the exact same dynamic method resolution point as every other method dispatch. At...
How to create a remote Git repository from a local one?
...e push/pull tracker for your local repository (git remote add origin URL), and then locally you just say git push origin master. Now any other repository can pull from the remote repository.
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How do I add a foreign key to an existing SQLite table?
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SQLite doesn't support the ADD CONSTRAINT variant of the ALTER TABLE command (sqlite.org: SQL Features That SQLite Does Not Implement).
Therefore, the only way to add a foreign key in sqlite 3.6.1 is during CREATE TABLE as follows:
CREATE TABLE child (
id INTEGER PRIMARY KEY,
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Pipe output and capture exit status in Bash
I want to execute a long running command in Bash, and both capture its exit status, and tee its output.
15 Answers
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Heap vs Binary Search Tree (BST)
What is the difference between a heap and BST?
8 Answers
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Regex to check whether a string contains only numbers [duplicate]
I get false on both "123" and "123f" . I would like to check if the hash only contains numbers. Did I miss something?
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