大约有 12,000 项符合查询结果（耗时：0.0188秒） [XML]
LEFT JOIN only first row
...t item, like so...
LEFT JOIN Person ON Person.id = (
SELECT SUBSTRING_INDEX(
GROUP_CONCAT(FirstName ORDER BY FirstName DESC SEPARATOR "_" ), '_', 1)
) FROM Person
);
Since we have DESC as our ORDER BY option, this will return a Person id for someone like "Zack". If we wanted some...
Accessing Imap in C# [closed]
... I liked to concept of S22.Imap. But What I am missing is accessing via index or message number.
– Tejasvi Hegde
Nov 7 '15 at 8:57
...
What is the difference between HAVING and WHERE in SQL?
...tion on the set returned by SQL; it uses SQL's built-in set oeprations and indexes and therefore is the fastest way to filter result sets. Always use WHERE whenever possible.
HAVING is necessary for some aggregate filters. It filters the query AFTER sql has retrieved, assembled, and sorted the re...
How to replace multiple white spaces with one white space
...c static string DontUseThisToCollapseSpaces(string text)
{
while (text.IndexOf(" ") != -1)
{
text = text.Replace(" ", " ");
}
return text;
}
This can loop forever. Anyone care to guess why? (I only came across this when it was asked as a newsgroup question a few years ago...
Good tutorials on XMPP? [closed]
...-jingle.jar
and documentation of
http://www.igniterealtime.org/downloads/index.jsp
Hope it helps others like it helped me
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Why aren't pointers initialized with NULL by default?
...this very reason, the operator[] of the vector class does not check if the index is out of bounds, for instance.
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Which SQL query is faster? Filter on Join criteria or Where clause?
...ilter then Join rather than Join then Filter. It was also able to use the index on that column because it didn't have to match Null. Query response changed from 61 seconds to 2 seconds.
– Ben Gripka
Sep 3 at 15:38
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Smallest data URI image possible for a transparent image
...n you make a GIF without a color table at all.
When you have a color table index defined as transparent, however, GIF decoders don’t seem to care that there isn’t actually a color table.
So I changed the logical screen descriptor to indicate there was no global color table and removed the table ...
How can I do an asc and desc sort using underscore.js?
... charCodeAt will "return the Unicode of the character at the specified index in a string" so it can be used to sort by characters in a string, but as shown it does not "sort by string" it sorts by a character in the string
– Anthony
May 22 '14 at 10:56
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How to get object size in memory? [duplicate]
...ytes for the
type object pointer, and I think 4 bytes for the sync block index. Why
is this additional overhead important? Well, let’s imagine we have a
class with two Int32 members; in this case, the memory requirement is
16 bytes and not 8.
...