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How to drive C#, C++ or Java compiler to compute 1+2+3+…+1000 at compile time?
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C# example to error at compile time.
class Foo
{
const char Sum = (1000 + 1) * 1000 / 2;
}
Produces the following compilation error:
Constant value '500500' cannot be converted to a 'char'
share
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How to disable/enable select field using jQuery?
...gt;
<label for="pizza">I would like to order a</label>
<select id="pizza_kind" name="pizza_kind">
<option>(choose one)</option>
<option value="margaritha">Margaritha</option>
<option value="hawai">Hawai</option>
</select>
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how to exclude null values in array_agg like in string_agg using postgres?
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SQL Fiddle
select
id,
(select array_agg(a) from unnest(canonical_users) a where a is not null) canonical_users,
(select array_agg(a) from unnest(non_canonical_users) a where a is not null) non_canonical_users
from (
SELE...
How to set selected value of jquery select2?
This belong to codes prior to select2 version 4
28 Answers
28
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jQuery to retrieve and set selected option value of html select element
I am attempting to retrieve and set the selected value of a select element (drop down list) with jQuery.
9 Answers
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SQL Server : Columns to Rows
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You can use the UNPIVOT function to convert the columns into rows:
select id, entityId,
indicatorname,
indicatorvalue
from yourtable
unpivot
(
indicatorvalue
for indicatorname in (Indicator1, Indicator2, Indicator3)
) unpiv;
Note, the datatypes of the columns you are unpivoting mus...
Select row with most recent date per user
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Query:
SQLFIDDLEExample
SELECT t1.*
FROM lms_attendance t1
WHERE t1.time = (SELECT MAX(t2.time)
FROM lms_attendance t2
WHERE t2.user = t1.user)
Result:
| ID | USER | TIME | IO |
---------------------------...
boost多索引容器multi_index_container实战 - C/C++ - 清泛网 - 专注C/C++及内核技术
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typedef std::vector<Person::ptr> Persons;
int main(int argc, char *argv[]) {
if (argc != 2) {
printf("Usage: program count\n");
return 0;
}
PersonContainer container;
IdPersons idPersons;
NamePersons namePersons;
p...
MySQL select 10 random rows from 600K rows fast
How can I best write a query that selects 10 rows randomly from a total of 600k?
26 Answers
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Why do we need argc while there is always a null at the end of argv?
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...Which is a shame, in a way. If we had int main(char *argv[], int argc, ...), then some programs could just omit the argc because they do not need it. Opposite (needing argc but not argv) is probably never useful in a real program.
– hyde
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