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How do you scroll up/down on the Linux console?
I recognize that Up / Down will give you the command history. But, how do you look at past output by scrolling up and down?
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How to check if field is null or empty in MySQL?
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Either use
SELECT IF(field1 IS NULL or field1 = '', 'empty', field1) as field1
from tablename
or
SELECT case when field1 IS NULL or field1 = ''
then 'empty'
else field1
end as field1
from tablename
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Create PostgreSQL ROLE (user) if it doesn't exist
...r fashion to what you had in mind:
DO
$do$
BEGIN
IF NOT EXISTS (
SELECT FROM pg_catalog.pg_roles -- SELECT list can be empty for this
WHERE rolname = 'my_user') THEN
CREATE ROLE my_user LOGIN PASSWORD 'my_password';
END IF;
END
$do$;
(Building on @a_horse_with_no_name's...
How to open existing project in Eclipse
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Project > Import > General > Select Root Directory > (do NOT select copy projects into workspace). This is useful if you use Eclipse outside scope of Java project as well, such as Ruby projects or C projects.
– JohnMerlino
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Is there any way to create a blank solution (.sln) file first and then add projects?
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Creating Solutions To create a new
solution
On the File menu, select New and then click Project.
In the Project types pane, select Other Project Types and
then select Visual Studio
Solutions.
In the Templates pane, select Blank Solution.
Enter a name for the project.
To chan...
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 to repeat the columns on SELECT to GROUP BY,...
Select Pandas rows based on list index
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For large datasets, it is memory efficient to read only selected rows via the skiprows parameter.
Example
pred = lambda x: x not in [1, 3]
pd.read_csv("data.csv", skiprows=pred, index_col=0, names=...)
This will now return a DataFrame from a file that skips all rows except 1 and ...
How to link a Facebook app with an existing fan page
...roducts").
Change your page name to mach your App name.
Go to your App and select "App Details"
Under "Contact Info" you will find "App Page". There you will be able to create a new page or if all went well, select your page from a list.
I found the info in the little question-mark next to "App pa...
How do I install cURL on cygwin?
...p.exe and the Category name is Net, in that look for package name curl and select it.
– Kuldeep Jain
Oct 19 '13 at 7:42
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IntelliJ: Working on multiple projects
...ven Projects" window (View > Tool Windows > Maven Projects) and then select the additional pom file you want to import.
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