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Postgresql aggregate array
... do something like this:
SELECT p.p_name,
STRING_AGG(Grade.Mark, ',' ORDER BY Grade.Mark) As marks
FROM Student
LEFT JOIN Grade ON Grade.Student_id = Student.Id
GROUP BY Student.Name;
EDIT
I am not sure. But maybe something like this then:
SELECT p.p_name,
array_to_string(ARRAY_AGG...
Ways to save enums in database
... Heart = 1,
Club = 3,
Diamond = 2,
Spade = 0 }
in order to maintain the legacy numerical values stored in the database.
How to sort them in the database
The question comes up: lets say i wanted to order the values. Some people may want to sort them by the enum's ordinal va...
Simplest way to do a recursive self-join?
... m.parentID = q.PersonID
)
SELECT *
FROM q
By adding the ordering condition, you can preserve the tree order:
WITH q AS
(
SELECT m.*, CAST(ROW_NUMBER() OVER (ORDER BY m.PersonId) AS VARCHAR(MAX)) COLLATE Latin1_General_BIN AS bc
FROM mytable m
...
How do I perform HTML decoding/encoding using Python/Django?
...issing the single-quote. This version includes an updated tuple, with the order of replacement reversed to avoid symmetric problems:
def html_decode(s):
"""
Returns the ASCII decoded version of the given HTML string. This does
NOT remove normal HTML tags like <p>.
"""
htm...
Why doesn't the height of a container element increase if it contains floated elements?
...k -->
<div style="clear: both;"></div>
<!-- Now in order to prevent the next div from floating beside the top ones,
we use `clear: both;`. This is like a wall, so now none of the div's
will be floated after this point. The container height will now also includ...
Why is the gets function so dangerous that it should not be used?
...
In order to use gets safely, you have to know exactly how many characters you will be reading, so that you can make your buffer large enough. You will only know that if you know exactly what data you will be reading.
Instead of...
Image fingerprint to compare similarity of many images
...d approach for improved comparison quality
A luminosity histogram (especially one that is separated into RGB components) is a reasonable fingerprint for an image - and can be implemented quite efficiently. Subtracting one histogram from another will produce a new historgram which you can process t...
T-SQL: Deleting all duplicate rows but keeping one [duplicate]
...e AS (
SELECT[foo], [bar],
row_number() OVER(PARTITION BY foo, bar ORDER BY baz) AS [rn]
FROM TABLE
)
DELETE cte WHERE [rn] > 1
Play around with it and see what you get.
(Edit: In an attempt to be helpful, someone edited the ORDER BY clause within the CTE. To be clear, you can order ...
Typedef function pointer?
...
I guess I'm just confused about the ordering. With typedef int (*func)(int), I understand that func is an alias, just a little confused because the alias is tangled with the type. Going by typedef int INT as an example I would be more of ease if typedef functio...
What does passport.session() middleware do?
...redentials, but rather the
unique cookie that identifies the session. In order to support login
sessions, Passport will serialize and deserialize user instances to
and from the session.
and
Note that enabling session support is entirely optional, though it is
recommended for most appli...