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Permanently Set Postgresql Schema Path
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for those wondering from the psql command line you can list schemas by \dn
– BKSpurgeon
Sep 30 '16 at 1:00
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Oracle Differences between NVL and Coalesce
...null as a from dual
) ;
succeeds.
More information : http://www.plsqlinformation.com/2016/04/difference-between-nvl-and-coalesce-in-oracle.html
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Postgres unique constraint vs index
... "master_unique_idx" UNIQUE, btree (ind_id)
In table description (\d in psql) you can tell unique constraint from unique index.
Uniqueness
Let's check uniqueness, just in case.
test=# insert into master values (0, 0);
INSERT 0 1
test=# insert into master values (0, 1);
ERROR: duplicate key val...
What is a domain specific language? Anybody using it? And in what way?
... system figures out the how.
Examples of DSL include all query languages (SQL, XPath, ...), all template languages (Django, Smarty, ...), shell scripts, especially including stuff like twill, a command driven web browser (mostly used for automated test), data storage and exchange languages (XML, YA...
How do you run a single query through mysql from the command line?
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mysql -u <user> -p -e "select * from schema.table"
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Get top n records for each group of grouped results
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Here is one way to do this, using UNION ALL (See SQL Fiddle with Demo). This works with two groups, if you have more than two groups, then you would need to specify the group number and add queries for each group:
(
select *
from mytable
where `group` = 1
order by...
Interface or an Abstract Class: which one to use?
...umber;
public $DateHired;
public function write_info(){
//sql codes here
echo "Writing ". $this->LastName . "'s info to emloyee dbase table <br>";
}
}
final class student extends person{
public $StudentNumber;
public $CourseName;
public functio...
Is it Linq or Lambda?
... of my code is of the "LINQ to Objects" variety. But if you have a lot of SQL experience, perhaps query syntax will be easier to understand at first.
– Tom Bushell
Sep 12 '11 at 18:32
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Combining INSERT INTO and WITH/CTE
...a table (either regular, or temp).
WITH common_table_expression (Transact-SQL)
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Access Denied for User 'root'@'localhost' (using password: YES) - No Privileges?
...ng the root password, we'll going to forcefully INSERT a record into the mysql.user table
In the init file, use this instead
INSERT INTO mysql.user (Host, User, Password) VALUES ('%', 'root', password('YOURPASSWORD'));
GRANT ALL ON *.* TO 'root'@'%' WITH GRANT OPTION;
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