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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 find duplicate values in a table in Oracle?
...est SQL statement that will return the duplicate values for a given column and the count of their occurrences in an Oracle database table?
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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...
Are the shift operators () arithmetic or logical in C?
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When shifting left, there is no difference between arithmetic and logical shift. When shifting right, the type of shift depends on the type of the value being shifted.
(As background for those readers unfamiliar with the difference, a "logical" right shift by 1 bit shifts all the bits ...
Checking the equality of two slices
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You need to loop over each of the elements in the slice and test. Equality for slices is not defined. However, there is a bytes.Equal function if you are comparing values of type []byte.
func testEq(a, b []Type) bool {
// If one is nil, the other must also be nil.
if (a ...
How do I get a human-readable file size in bytes abbreviation using .NET?
... to do it, but it's easier to read if you are not familiar with log maths, and should be fast enough for most scenarios.
string[] sizes = { "B", "KB", "MB", "GB", "TB" };
double len = new FileInfo(filename).Length;
int order = 0;
while (len >= 1024 && order < sizes.Length - 1) {
o...
Check whether number is even or odd
...r is even or odd? I've been wanting to figure this out for a long time now and haven't gotten anywhere.
16 Answers
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Why should I use Hamcrest-Matcher and assertThat() instead of traditional assertXXX()-Methods
...ormation from assertTrue.
assertThat will tell you what the assertion was and what you got instead. assertTrue will only tell you that you got false where you expected true.
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Finding the number of days between two dates
...I think returning a negative number of days provides relevant information. And you should be using $your_date-$now, if you want a future date to return a positive integer.
– Tim
Mar 2 '12 at 18:49
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Preferred order of writing latitude & longitude tuples in GIS services
When dealing with GIS source code you often need to write latitude and longitude coordinate tuples.
9 Answers
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