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Kill a postgresql session/connection
...g the database.
def drop_database(config)
case config['adapter']
when /mysql/
ActiveRecord::Base.establish_connection(config)
ActiveRecord::Base.connection.drop_database config['database']
when /sqlite/
require 'pathname'
path = Pathname.new(config['database'])
file = path....
How do I modify fields inside the new PostgreSQL JSON datatype?
...FROM json_each("json")
WHERE "key" <> "key_to_set"
UNION ALL
SELECT "key_to_set", to_json("value_to_set")) AS "fields"
$function$;
SQLFiddle
Edit:
A version, which sets multiple keys & values:
CREATE OR REPLACE FUNCTION "json_object_set_keys"(
"json" j...
how to exclude null values in array_agg like in string_agg using postgres?
...array[null]:
select
array_agg(x)-array['']
from
( select 'Y' x union all
select null union all
select 'N' union all
select ''
) x;
That's all:
{Y, N}
share
|
...
What is the fastest or most elegant way to compute a set difference using Javascript arrays?
...
Why JavaScript sets don't have union/intersect/difference built in is beyond me...
– SwiftsNamesake
Nov 27 '16 at 4:50
6
...
CMake使用教程 - C/C++ - 清泛网 - 专注C/C++及内核技术
...中找到这个手册对应的代码。
1、Step1。
（如果不知道如何使用cmake，以及如何使用编译产生的Turorial.exe，可先看下前面“CMake使用步骤”的说明，它以Step4为例详细介绍了使用过程，Step1的配置可能不够完全，比如无法运行make...
Difference between left join and right join in SQL Server [duplicate]
...i
Null Null Kathmandu
Full Join
Note : It is same as union operation, it will return all selected values from both tables.
Syntax:
SELECT column_name(s) FROM table1 FULL OUTER JOIN table2 ON table1.column_name = table2.column_name;
Apply it in your samp[le table:
SELECT...
Nginx serves .php files as downloads, instead of executing them
...ttps://www.digitalocean.com/community/tutorials/how-to-install-linux-nginx-mysql-php-lemp-stack-on-ubuntu-14-04 but when I try to run some .php file it's just downloading it...
for example... http://5.101.99.123/info.php it's working but... If I go to the main http://5.101.99.123 it's downloadi...
What is the difference between HashSet and List?
...ady existing in Set
Can perform mathematical set operations against a Set: Union/Intersection/IsSubsetOf etc.
HashSet doesn't implement IList only ICollection
You cannot use indices with a HashSet, only enumerators.
The main reason to use a HashSet would be if you are interested in performing Set ...
Where is C not a subset of C++? [closed]
...
In C++, if you declare a struct, union, or enum, its name is immediately accessible without any qualifiers:
struct foo { ... };
foo x; // declare variable
In C, this won't work, because types thus declared live in their own distinct namespaces. Thus, you ...
Hidden Features of Java
...
Joint union in type parameter variance:
public class Baz<T extends Foo & Bar> {}
For example, if you wanted to take a parameter that's both Comparable and a Collection:
public static <A, B extends Collection<A&g...