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What's the purpose of SQL keyword “AS”?
...ProductRetailPrice,
O.Quantity
FROM Products AS P
LEFT OUTER JOIN Orders AS O ON O.ProductID = P.ProductID
WHERE O.OrderID = 123456
Example 3
It's a good practice to use the AS keyword, and very recommended, but it is possible to perform the same query without one (and I do often).
SELE...
MySQL INNER JOIN select only one row from second table
... = (
SELECT id
FROM payments AS p2
WHERE p2.user_id = u.id
ORDER BY date DESC
LIMIT 1
)
Or
SELECT u.*, p.*
FROM users AS u
INNER JOIN payments AS p ON p.user_id = u.id
WHERE NOT EXISTS (
SELECT 1
FROM payments AS p2
WHERE
p2.user_id = p.user_id AND
(p...
Is there any way to put malicious code into a regular expression?
...ar Expression Matching Can Be Simple And Fast
(but is slow in Java, Perl, PHP, Python, Ruby, ...) talks about ways that most modern NFAs, which all seem to derive from Henry Spencer’s code, suffer severe performance degradation, but where a Thompson‐style NFA has no such problems.
If you only ...
What is the difference between atomic and critical in OpenMP?
...d. We are referring to those cases that synchronization is necessary.
In order to synchronize the threads in a multi-threaded program, we'll use lock. When the access is required to be restricted by only one thread at a time, locks come into play. The lock concept implementation may vary from proc...
How to get Last record from Sqlite?
...LE);
OR
you can also used following solution:
SELECT * FROM tablename ORDER BY column DESC LIMIT 1;
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Switch statement: must default be the last case?
...
The case statements and the default statement can occur in any order in the switch statement. The default clause is an optional clause that is matched if none of the constants in the case statements can be matched.
Good Example :-
switch(5) {
case 1:
echo "1";
break;
case ...
Iterator invalidation rules
...ct the validity of iterators and references to the container [26.2.6/9]
Unordered Associative Containers
All Unordered Associative Containers: Rehashing invalidates iterators, changes ordering between elements, and changes which buckets elements appear in, but does not invalidate pointers or refer...
Mapping a function on the values of a map in Clojure
...
I like it, but is there any reason for the arguments order (besides the question) ? I was expecting [f m] as in map for some reason.
– nha
Aug 21 '16 at 22:48
...
How does one reorder columns in a data frame?
...s keep all the rows, and the 1,2,3,4 refers to the columns.
To change the order as in the above question do df2[,c(1,3,2,4)]
If you want to output this file as a csv, do write.csv(df2, file="somedf.csv")
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Why is the minimalist, example Haskell quicksort not a “true” quicksort?
...cksort actually behaves in Haskell in terms of memory accesses or even the order of comparisons. If you could only observe the behavior, and not the source code, you would not recognize what it's doing as a quicksort.
For example, the C version of quicksort partitions all the data before the first ...