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SQL - using alias in Group By
...d because they must have been introduced in a previous step.
So in Oracle and SQL Server, you cannot use a term in the GROUP BY clause that you define in the SELECT clause because the GROUP BY is executed before the SELECT clause.
There are exceptions though: MySQL and Postgres seem to have additi...
How do I check if a number evaluates to infinity?
...lert(x === Infinity); displays "true". (Admittedly that's an obscure case, and anyone who decides to redefine Infinity, NaN etc should expect odd things to happen.)
– LukeH
Jan 18 '11 at 13:49
...
WordPress is giving me 404 page not found for all pages except the homepage
All of a sudden I go to my WordPress website and all the pages give me a 404 page not found page. I'm assuming the problem lies with the permalink structure, which I could swear I did not touch. The permalink setting is on "month and name."
...
Tricky Google interview question
... = 0; // Index for 5
int x2 = 2 * v[i2]; // Next two candidates
int x5 = 5 * v[i5];
for (int i = 1; i != n; ++i)
{
int m = std::min(x2, x5);
std::cout << m << " ";
v[i] = m;
if (x2 == m)
{
++i2;
...
How to convert AAR to JAR
...
The AAR file consists of a JAR file and some resource files (it is basically a standard zip file with a custom file extension). Here are the steps to convert:
Extract the AAR file using standard zip extract (rename it to *.zip to make it easier)
Find the clas...
Abort makefile if variable not set
...ning an auxiliary function for that:
# Check that given variables are set and all have non-empty values,
# die with an error otherwise.
#
# Params:
# 1. Variable name(s) to test.
# 2. (optional) Error message to print.
check_defined = \
$(strip $(foreach 1,$1, \
$(call __check_defin...
iReport not starting using JRE 8
I have downloaded and installed the iReport 4.5 using te Windows installer. But when I try to start the iReport it shows the splash screen but does not start.
...
Compare two data.frames to find the rows in data.frame 1 that are not present in data.frame 2
...re allowed (e.g. changing order of elements of each vector, changing order and names of variables, shortening variables, changing case of strings). From this, you should be able to figure out what was missing from one or the other. For example (this is not very elegant):
difference <-
data.fr...
Given a class, see if instance has method (Ruby)
...don't know why everyone is suggesting you should be using instance_methods and include? when method_defined? does the job.
class Test
def hello; end
end
Test.method_defined? :hello #=> true
NOTE
In case you are coming to Ruby from another OO language OR you think that method_defined means ...
How do I use a Boolean in Python?
...
Actually Python didn't have a boolean type for a long time (as in old C), and some programmers still use integers instead of booleans.
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