大约有 15,000 项符合查询结果（耗时：0.0157秒） [XML]
How to get all possible combinations of a list’s elements?
... you pick all elements corresponding to a "1".
items=abc * mask=###
|
V
000 ->
001 -> c
010 -> b
011 -> bc
100 -> a
101 -> a c
110 -> ab
111 -> abc
Things to consider:
This requires that you can call len(...) on items (workaround: if items is something like an ite...
Comparing date part only without comparing time in JavaScript
...etHours(0,0,0,0); console.log(t.toJSON()); will print "2016-02-28T15:00:00.000Z", date 28, but not 29 My current time zone is Asia/Tokyo
– transang
Feb 29 '16 at 2:43
9
...
How would you implement an LRU cache in Java?
... );
cache.put ( 3, 3 );
for (int index =0 ; index < 5_000; index++) {
cache.get(0);
cache.get ( 1 );
cache.put ( 2, index );
cache.put ( 3, index );
cache.put(index, index);
}
boolean ok = cache.getSil...
Which are more performant, CTE or temporary tables?
...cs.
Test Data
CREATE TABLE T(A INT IDENTITY PRIMARY KEY, B INT , F CHAR(8000) NULL);
INSERT INTO T(B)
SELECT TOP (1000000) 0 + CAST(NEWID() AS BINARY(4))
FROM master..spt_values v1,
master..spt_values v2;
Example 1
WITH CTE1 AS
(
SELECT A,
ABS(B) AS Abs_B,
F
FROM T
)
SELECT...
Are loops really faster in reverse?
...j=i+1, i=j.]]
Really fast loops can be done by unrolling them:
for(i=800000;i>0;--i)
do_it(i);
It can be way slower than
for(i=800000;i>0;i-=8)
{
do_it(i); do_it(i-1); do_it(i-2); ... do_it(i-7);
}
but the reasons for this can be quite complicated (just to mention, there are ...
How to parse XML in Bash?
...m-apple-iso@2x.png</Key>
<LastModified>2011-07-25T22:23:04.000Z</LastModified>
<ETag>&quot;0032a28286680abee71aed5d059c6a09&quot;</ETag>
<Size>1785</Size>
<StorageClass>STANDARD</StorageClass>
</Contents>
</List...
SQL Server : Columns to Rows
...me that xml is about 2.5 times slower that dynamic (it was one query on ~250000 rows table, so this estimate is no way exact). You could compare it yourself if you want, here's sqlfiddle example, on 100000 rows it was 29s (xml) vs 14s (dynamic);
may be it could be harder to understand for people not...
Check if a Postgres JSON array contains a string
...te: Here's a demonstration of the performance improvements on a table of 1,000,000 rabbits where each rabbit likes two foods and 10% of them like carrots:
d=# -- Postgres 9.3 solution
d=# explain analyze select info->>'name' from rabbits where exists (
d(# select 1 from json_array_elements(in...
How can I position my div at the bottom of its container?
...argin-top: auto;
}
.parent {
height: 100px;
border: 5px solid #000;
display: flex;
flex-direction: column;
}
.child {
height: 40px;
width: 100%;
background: #f00;
margin-top: auto;
}
<div class="parent">
<div class="child">Align to the bottom</div&...
Do sealed classes really offer performance Benefits?
...Release build configuration) emits identical MSIL, which is as follows:
L_0000: newobj instance void <NormalClass or SealedClass>::.ctor()
L_0005: stloc.0
L_0006: ldloc.0
L_0007: ldstr "a string"
L_000c: callvirt instance void <NormalClass or SealedClass>::WriteIt(string)
L_0011: ret ...