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Subtract two variables in Bash
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You just need a little extra whitespace around the minus sign, and backticks:
COUNT=`expr $FIRSTV - $SECONDV`
Be aware of the exit status:
The exit status is 0 if EXPRESSION is neither null nor 0, 1 if EXPRESSION is null or 0.
Keep this in mind when using the expression in a bash sc...
What is the facade design pattern?
...erns are just normal classes. What is important is how they are structured and how they work together to solve a given problem in the best possible way.
The Facade design pattern simplifies the interface to a complex system; because it is usually composed of all the classes which make up the subsy...
How do I detect what .NET Framework versions and service packs are installed?
...ncies, .NET 3.0 adds additional functionality to .NET 2.0 so both .NET 2.0 and .NET 3.0 must both evaulate as being installed to correctly say that .NET 3.0 is installed. Likewise, .NET 3.5 adds additional functionality to .NET 2.0 and .NET 3.0, so .NET 2.0, .NET 3.0, and .NET 3. should all evaluate...
How to compare versions in Ruby?
How to write a piece of code to compare some versions strings and get the newest?
8 Answers
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GROUP BY with MAX(DATE) [duplicate]
...able
GROUP BY Train
) r
INNER JOIN TrainTable t
ON t.Train = r.Train AND t.Time = r.MaxTime
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Take screenshots in the iOS simulator
...ke a screenshot of my iOS application when it is running in the simulator, and save the screenshot on my Mac. How can I do this?
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How to hide a button programmatically?
...lic void onClick(View v) {
//when play is clicked show stop button and hide play button
playButton.setVisibility(View.GONE);
stopButton.setVisibility(View.VISIBLE);
}
});
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How to implement one-to-one, one-to-many and many-to-many relationships while designing tables?
Can anyone explain how to implement one-to-one, one-to-many and many-to-many relationships while designing tables with some examples?
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What is reflection and why is it useful?
What is reflection, and why is it useful?
21 Answers
21
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Create a temporary table in a SELECT statement without a separate CREATE TABLE
...only) table from a select statement without using a create table statement and specifying each column type? I know derived tables are capable of this, but those are super-temporary (statement-only) and I want to re-use.
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