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SQL: How to properly check if a record exists
...HERE unique_key = value;
The first alternative should give you no result or one result, the second count should be zero or one.
How old is the documentation you're using? Although you've read good advice, most query optimizers in recent RDBMS's optimize SELECT COUNT(*) anyway, so while there is a...
An invalid form control with name='' is not focusable
...omers are not able to proceed to my payment page.
When trying to submit a form I get this error:
35 Answers
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How do I create a category in Xcode 6 or higher?
I want to create a category on UIColor in my app using Xcode 6. But the thing is that in Xcode 6 there is no Objective-C category file template.
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How to print last two columns using awk
...of variable NF which is set to the total number of fields in the input record:
awk '{print $(NF-1),"\t",$NF}' file
this assumes that you have at least 2 fields.
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Sorting an ArrayList of objects using a custom sorting order
I am looking to implement a sort feature for my address book application.
11 Answers
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How to find out how many lines of code there are in an Xcode project?
...any lines of code an Xcode project contains? I promise not to use such information for managerial measurement or employee benchmarking purposes. ;)
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Const before or const after?
...you probably know that const can be used to make either an object's data or a pointer not modifiable or both.
7 Answers
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How to take the first N items from a generator or list in Python? [duplicate]
...e all valid: array[start:], array[:stop], array[::step]
Slicing a generator
import itertools
top5 = itertools.islice(my_list, 5) # grab the first five elements
You can't slice a generator directly in Python. itertools.islice() will wrap an object in a new slicing generator using the syntax i...
How to check if a variable is set in Bash?
... does not require quotes (since it either expands to x (which contains no word breaks so it needs no quotes), or to nothing (which results in [ -z ], which conveniently evaluates to the same value (true) that [ -z "" ] does as well)).
However, while quotes can be safely omitted, and it was not imm...
How to draw vertical lines on a given plot in matplotlib?
Given a plot of signal in time representation, how to draw lines marking corresponding time index?
6 Answers
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