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What is the “N+1 selects problem” in ORM (Object-Relational Mapping)?
The "N+1 selects problem" is generally stated as a problem in Object-Relational mapping (ORM) discussions, and I understand that it has something to do with having to make a lot of database queries for something that seems simple in the object world.
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What is “Argument-Dependent Lookup” (aka ADL, or “Koenig Lookup”)?
...eems a bit backwards. I would expect the problem do be when std::swap() is selected rather than the overload specific to the type, A::swap(). The example with std::swap(A::MyClass&, A::MyClass&) seems misleading. since std would never have a specific overload for a user type, I don't think i...
Can I call memcpy() and memmove() with “number of bytes” set to zero?
...values, as described in 7.1.4. On such a call, a
function that locates a character finds no occurrence, a function that compares two
character sequences returns zero, and a function that copies characters copies zero
characters.
So the answer is no; the check is not necessary (or yes; you ca...
Get value when selected ng-option changes
...ple:
<div ng-app="App" >
<div ng-controller="ctrl">
<select ng-model="blisterPackTemplateSelected" ng-change="changedValue(blisterPackTemplateSelected)"
data-ng-options="blisterPackTemplate as blisterPackTemplate.name for blisterPackTemplate in blisterPackTemplates...
Can I use a binary literal in C or C++?
...namespace std;
int main() {
unsigned short b = BOOST_BINARY( 10010 );
char buf[sizeof(b)*8+1];
printf("hex: %04x, dec: %u, oct: %06o, bin: %16s\n", b, b, b, itoa(b, buf, 2));
cout << setfill('0') <<
"hex: " << hex << setw(4) << b << ", " <<
...
How to reset postgres' primary key sequence when it falls out of sync?
...
-- Login to psql and run the following
-- What is the result?
SELECT MAX(id) FROM your_table;
-- Then run...
-- This should be higher than the last result.
SELECT nextval('your_table_id_seq');
-- If it's not higher... run this set the sequence last to your highest id.
-- (wise to run...
How to randomly select rows in SQL?
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SELECT TOP 5 Id, Name FROM customerNames
ORDER BY NEWID()
That said, everybody seems to come to this page for the more general answer to your question:
Selecting a random row in SQL
Select a random row with MySQL:
SELECT...
Select random row from a sqlite table
...
Have a look at Selecting a Random Row from an SQLite Table
SELECT * FROM table ORDER BY RANDOM() LIMIT 1;
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Select first row in each GROUP BY group?
As the title suggests, I'd like to select the first row of each set of rows grouped with a GROUP BY .
17 Answers
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What is a higher kinded type in Scala?
...va 5 generics are first-order.
The first-order interpretation of the above characterizations of abstractions are:
A type constructor is a type that you can apply to proper type arguments to "construct" a proper type.
A value constructor is a value that you can apply to proper value arguments to "co...