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SQL/mysql - Select distinct/UNIQUE but return all columns?
... MySQL, if that's what you're using.)
You could fetch the distinct fields and stick to picking a single arbitrary row each time.
On some platforms (e.g. PostgreSQL, Oracle, T-SQL) this can be done directly using window functions:
select *
from (
select *,
row_number() over (partition...
How to delete duplicate lines in a file without sorting it in Unix?
... last line if the file has an even number of lines.
To convert scripts which used the former behavior of N (deleting
the pattern space upon reaching the EOF) to scripts compatible with
all versions of sed, change a lone "N;" to "$d;N;".
...
How to find the key of the largest value hash?
...0], *hash[hash.length-1]
2nd largest key value pair
Hash[*hash[1]]
To convert the hash array back into a hash
hash.to_h
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How do you cast a List of supertypes to a List of subtypes?
... methods.
Filtering the list based on the type
A more type-safe way of converting from a List<Supertype> to a List<Subtype> is to actually filter the list, and create a new list that contains only elements that have certain type. There are some degrees of freedom for the implementat...
SQLite select where empty?
...n I select records where some_column is empty?
Empty counts as both NULL and "".
4 Answers
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How do I iterate through each element in an n-dimensional matrix in MATLAB?
... ind2sub in the loop
for ii=1:nel
[ szargs{:} ] = ind2sub( sz, ii ); % Convert linear index back to subscripts
if all( [szargs{2:end}] == szargs{1} ) % On the diagonal?
d( ii ) = 1;
end
end
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What's the best way to check if a file exists in C?
...exists
} else {
// file doesn't exist
}
You can also use R_OK, W_OK, and X_OK in place of F_OK to check for read permission, write permission, and execute permission (respectively) rather than existence, and you can OR any of them together (i.e. check for both read and write permission using R...
Load “Vanilla” Javascript Libraries into Node.js
...liked a second mechanism to include external files, one that automatically converted the included file's global namespace to the imported namespace. Perhaps you could file a RFE to the Node developers?
– Martijn
Mar 3 '11 at 7:02
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Implementing two interfaces in a class with same method. Which interface method is overridden?
Two interfaces with same method names and signatures. But implemented by a single class then how the compiler will identify the which method is for which interface?
...
What is the Java ?: operator called and what does it do?
...
Yes, it is a shorthand form of
int count;
if (isHere)
count = getHereCount(index);
else
count = getAwayCount(index);
It's called the conditional operator. Many people (erroneously) call it the ternary operator, because it's the only te...