大约有 6,884 项符合查询结果（耗时：0.0198秒） [XML]
Generating random strings with T-SQL
...se of an off-by-one error: SUBSTRING(..., 0, ...) returns empty string for index 0, and for 529126 this 'hides' the first character generated. Fix is to compute @dice = rand(@seed) * len(@specials)+1 to make the indexes 1 based.
– Remus Rusanu
Feb 17 '16 at 13:...
Best practices for SQL varchar column length [closed]
...
@Ariel: There are issues and limitations on indexes to consider, too. You can't have a (a,b,c,d) index when all four columns are VARCHAR(255).
– ypercubeᵀᴹ
Nov 28 '11 at 23:30
...
Best way to select random rows PostgreSQL
... few) gaps.
Obviously no or few write operations.
Your ID column has to be indexed! A primary key serves nicely.
The query below does not need a sequential scan of the big table, only an index scan.
First, get estimates for the main query:
SELECT count(*) AS ct -- optional
, mi...
Is there a short contains function for lists?
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The list method index will return -1 if the item is not present, and will return the index of the item in the list if it is present. Alternatively in an if statement you can do the following:
if myItem in list:
#do things
You can also...
Yii2 data provider default sorting
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This solution works but the search in index doesn't work now.
– Roby Sottini
Nov 16 '17 at 12:14
add a comment
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Split a List into smaller lists of N size
... to nSize? For example if nSize is 3 and my array is size 5 then the first index range returned is GetRange(3, 3)
– Matthew Pigram
Mar 22 '18 at 1:11
2
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Modify request parameter with servlet filter
...(int i = 0; i < input.length(); i++) {
if (allowedChars.indexOf(input.charAt(i)) >= 0) {
result += input.charAt(i);
}
}
return result;
}
public String getParameter(String paramName) {
Strin...
Iterating C++ vector from the end to the beginning
.../ Process `*iterator`
}
This pattern is useful, for example, for reverse-indexing an array using an unsigned index
int array[N];
...
// Iterate over [0, N) range in reverse
for (unsigned i = N; i-- != 0; ) {
array[i]; // <- process it
}
(People unfamiliar with this pattern often insist on ...
Django dynamic model fields
... name = models.CharField(max_length=32)
data = models.HStoreField(db_index=True)
In Django's shell you can use it like this:
>>> instance = Something.objects.create(
name='something',
data={'a': '1', 'b': '2'}
)
>>> insta...
Center a 'div' in the middle of the screen, even when the page is scrolled up or down?
...r {
height: 60%;
left: 50%;
position: absolute;
top: 50%;
z-index: 10;
width: 60%;
}
#message .container .text {
background: #fff;
height: 100%;
left: -50%;
position: absolute;
top: -50%;
width: 100%;
}
#message .bg {
background: rgba(0, 0, 0, 0.5);
...