大约有 45,000 项符合查询结果（耗时：0.0405秒） [XML]
When to use Common Table Expression (CTE)
...ing well? Can someone give me a simple example of limitations with regular select, derived or temp table queries to make the case of CTE? Any simple examples would be highly appreciated.
...
Which is fastest? SELECT SQL_CALC_FOUND_ROWS FROM `table`, or SELECT COUNT(*)
...irm this - I just updated a query with 4 joins on a 168,000 row database. Selecting just the first 100 rows with a SQL_CALC_FOUND_ROWS took over 20 seconds; using a separate COUNT(*) query took under 5 seconds (for both count + results queries).
– Sam Dufel
Ju...
.net implementation of bcrypt
...
Article moved: chargen.matasano.com/chargen/2007/9/7/enough-with-the-rainbow- tables-what-you-need-to-know-about-s.html
– Code Silverback
May 7 '12 at 13:46
...
C++ STL Vectors: Get iterator from index?
... legal to do this folowing, according to me:
int main()
{
void foo(const char *);
sdt::vector<char> vec;
vec.push_back('h');
vec.push_back('e');
vec.push_back('l');
vec.push_back('l');
vec.push_back('o');
vec.push_back('/0');
foo(&vec[0]);
}
Of course, either foo must not copy the ad...
Extracting an attribute value with beautifulsoup
...have a question about parsing the output which i a long bunch of non-ASCII chars but I will ask this in a separate question.
– Barnabe
Apr 10 '10 at 7:33
3
...
How do I toggle an element's class in pure JavaScript?
...e seperators. for example it doesn't work if class name contain dash ("-") char: btn, btn-red will both match'\\b' + 'btn' + '\\b' !!
– S.Serpooshan
Feb 5 '19 at 6:47
...
Using LIMIT within GROUP BY to get N results per group?
...to get all years into a single column, grouped by id and ordered by rate:
SELECT id, GROUP_CONCAT(year ORDER BY rate DESC) grouped_year
FROM yourtable
GROUP BY id
Result:
-----------------------------------------------------------
| ID | GROUPED_YEAR |...
Select all DIV text with single mouse click
How to highlight/select the contents of a DIV tag when the user clicks on the DIV...the idea is that all of the text is highlighted/selected so the user doesn't need to manually highlight the text with the mouse and potentially miss a bit of the text?
...
SQL Server Insert if not exists
..., Assunto, Data)
VALUES (@_DE, @_ASSUNTO, @_DATA)
WHERE NOT EXISTS ( SELECT * FROM EmailsRecebidos
WHERE De = @_DE
AND Assunto = @_ASSUNTO
AND Data = @_DATA);
END
replace with
BEGIN
IF NOT EXISTS (SELECT * FROM EmailsRecebidos
...
MySQL ON vs USING?
...n tables ON a column, a set of columns and even a condition. For example:
SELECT * FROM world.City JOIN world.Country ON (City.CountryCode = Country.Code) WHERE ...
USING is useful when both tables share a column of the exact same name on which they join. In this case, one may say:
SELECT ... FR...