大约有 25,000 项符合查询结果（耗时：0.0375秒） [XML]
Postgresql aggregate array
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Use array_agg: http://www.sqlfiddle.com/#!1/5099e/1
SELECT s.name, array_agg(g.Mark) as marks
FROM student s
LEFT JOIN Grade g ON g.Student_id = s.Id
GROUP BY s.Id
By the way, if you are using Postgres 9.1, you don't need ...
What are the differences between Perl, Python, AWK and sed? [closed]
...th an ⁿ of 1,000,000 it runs in less than two seconds. time perl -E '$x=1_000_000;$_="a"x$x;$m=("a??"x$x).("a"x$x);say $_=~$m' If you run the naive one it takes more than two seconds for an ⁿ of just 25. The thing you have to realize is Perl has more regex features than those faster ones includi...
What is a stored procedure?
...tatype>
AS
<Body>
So for example:
CREATE PROCEDURE Users_GetUserInfo
@login nvarchar(30)=null
AS
SELECT * from [Users]
WHERE ISNULL(@login,login)=login
A benefit of stored procedures is that you can centralize data access logic into a single place that is then eas...
Clearing intent
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answered Feb 11 '13 at 21:06
SlynkSlynk
46744 silver badges99 bronze badges
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Aggregate function in an SQL update query?
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edited Jan 6 '10 at 1:06
answered Jan 5 '10 at 23:32
JB...
How can I negate the return-value of a process?
...c,v $
@(#)Version: $Revision: 4.2 $
@(#)Last changed: $Date: 2005/06/22 19:44:07 $
@(#)Purpose: Invert success/failure status of command
@(#)Author: J Leffler
@(#)Copyright: (C) JLSS 1991,1997,2005
*/
#include <stdlib.h>
#include <unistd.h>
#include <sys/...
LEN function not including trailing spaces in SQL Server
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I would use LEN(REPLACE(expr, ' ', '_')). This should work with varchar and nvarchar and strings containing special unicode control characters.
– Olivier Jacot-Descombes
Apr 24 '14 at 16:01
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What is the performance cost of having a virtual method in a C++ class?
... be non-virtual is an abominable policy.
– underscore_d
May 20 '17 at 19:34
add a comment
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What is the difference between encrypting and signing in asymmetric encryption?
...me in pairs.
– slim
Jul 4 '15 at 18:06
3
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What's the difference between .so, .la and .a library files?
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edited Sep 7 '18 at 0:06
answered Sep 2 '12 at 16:16
Ba...