大约有 44,000 项符合查询结果（耗时：0.0539秒） [XML]
I want to get the type of a variable at runtime
... case _: B => "A is a B"
case _ => "A is not a B"
}
f(x, y) // A (Char) is not a B (Int)
f(x, z) // A (Char) is a B (Any)
Here I'm using the context bounds syntax, B : ClassTag, which works just like the implicit parameter in the previous ClassTag example, but uses an anonymous variable.
...
Generate GUID in MySQL for existing Data?
...e BEFORE UPDATE on YourTable
FOR EACH ROW
BEGIN
SET new.guid_column := (SELECT UUID());
END
//
Then execute
UPDATE YourTable set guid_column = (SELECT UUID());
And DROP TRIGGER beforeYourTableUpdate;
UPDATE
Another solution that doesn't use triggers, but requires primary key or unique inde...
Determining 32 vs 64 bit in C++
...lt;sizeof(size_t)>(); }
int main()
{
// appropriate function will be selected at compile time
DoMyOperation();
return 0;
}
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How to split a string in shell and get the last field
...ecially handy when parsing paths that could contain (or not) a finishing / character.
– eckes
Jan 23 '13 at 15:23
...
What is the meaning of id?
...ion rules. For example, with a void * pointer you can't do this:
void *x;
char *y = x; // error, this needs an explicit cast
On the contrary, it's possible with id:
id x;
NSString *y = x;
See more usage of type id in objective c examples.
In addition in the "modern" Objective C it's preferred...
How can I select rows with most recent timestamp for each key value?
...r data. Each row has a sensor id, a timestamp, and other fields. I want to select a single row with latest timestamp for each sensor, including some of the other fields.
...
Mongoose, Select a specific field with find
I'm trying to select only a specific field with
8 Answers
8
...
LINQ to SQL - Left Outer Join with multiple join conditions
...g.Where(f => f.otherid == 17).DefaultIfEmpty()
where p.companyid == 100
select f.value
Or you could use a subquery:
from p in context.Periods
join f in context.Facts on p.id equals f.periodid into fg
from fgi in (from f in fg
where f.otherid == 17
select f).DefaultIfE...
How to hide a in a menu with CSS?
...hat Chrome, it seems, will not allow me to hide <option> in a <select> . Firefox will.
13 Answers
...
SQLAlchemy IN clause
...3,456))).all()
edit: Without the ORM, it would be
session.execute(
select(
[MyUserTable.c.id, MyUserTable.c.name],
MyUserTable.c.id.in_((123, 456))
)
).fetchall()
select() takes two parameters, the first one is a list of fields to retrieve, the second one is the where ...