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Postgresql aggregate array
...) 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 to repeat the columns on SELECT to GROUP BY, e.g. you don't need to repeat the student name on GROUP BY. You can merely GROUP BY on primary key. If you...
PHP操作MongoDB时的整数问题及对策 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...DB。
那么PHP驱动真的完全解决了整数问题么？NO！在处理group操作的时候还有BUG：
为了说明问题，我们先来生成一些测试数据：
<?php
ini_set('mongo.native_long', 1);
$instance = new Mongo();
$instance = $instance->selectCollection('test', 'test'...
Access is denied when attaching a database
...sions to the mdf and ldf files. However, it had those permissions through group membership (the Local Administrators group had permissions, and my account is a member of local admins). (I verified the permissions)
If I try to do the attach, connect to SQL Server as me (where I am in the admins g...
How to find nth occurrence of character in a string?
... Matcher m = p.matcher(in);
if (m.matches())
return m.group(2);
else
return null;
}
}
Note that I did some assumptions in the regex:
the input path is absolute (i.e. starts with "/");
you do not need the 3rd "/" in the result.
As requested in a co...
Set selected index of an Android RadioGroup
Is there a way to set the selected index of a RadioGroup in android, other than looping through the child radiobuttons and selecting checking the radio button at the selected index?
...
C# Test if user has write access to a folder
...eful.
string path = @"c:\temp";
string NtAccountName = @"MyDomain\MyUserOrGroup";
DirectoryInfo di = new DirectoryInfo(path);
DirectorySecurity acl = di.GetAccessControl(AccessControlSections.All);
AuthorizationRuleCollection rules = acl.GetAccessRules(true, true, typeof(NTAccount));
//Go through...
How to add a search box with icon to the navbar in Bootstrap 3?
...lt;form class="navbar-form" role="search">
<div class="input-group">
<input type="text" class="form-control" placeholder="Search" name="srch-term" id="srch-term">
<div class="input-group-btn">
<button class="btn btn-default" typ...
XSD - how to allow elements in any order any number of times?
...lexType>
If we want to minimize the bulk a bit, we can define a named group for the repeating choices of child1 and child2:
<xsd:group name="onetwo">
<xsd:choice>
<xsd:element ref="child1"/>
<xsd:element ref="child2"/>
</xsd:choice>
</xsd:group&g...
Mongod complains that there is no /data/db folder
.../data/db/
The left side 'drwxr-xr-x' shows the permissions for the User, Group, and Others.
'mongod mongod' shows who owns the directory, and which group that directory belongs to.
Both are called 'mongod' in this case.
If your '/data/db' directory doesn't have the permissions and ownership abo...
SQL to find the number of distinct values in a column
...
also works on groups select A,COUNT(DISTINCT B) from table group by A
– tmanthey
Apr 18 '13 at 15:07
7
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