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How to delete duplicates on a MySQL table?
...n an index is going to be slow for large tables. Wouldn't it be better to SELECT MAX(ID) FROM t GROUP BY unique and then JOIN to an exact match of ID to MAX(ID)?
– ebyrob
Nov 10 '16 at 16:31
...
Using group by on multiple columns
..., to do with who is attending what subject at a university:
Table: Subject_Selection
+---------+----------+----------+
| Subject | Semester | Attendee |
+---------+----------+----------+
| ITB001 | 1 | John |
| ITB001 | 1 | Bob |
| ITB001 | 1 | Mickey |
| ITB001 ...
How do I pass command line arguments to a Node.js program?
...ecause options that start with a single dash are only supposed to a single character. Anything that follows a single char option is taken as an argument for the option (no space required). Starting the option with two dashes (i.e. --n5) should produce 'n5: true'. This is fairly standard behaviour fo...
how do I query sql for a latest record date for each user
...
select t.username, t.date, t.value
from MyTable t
inner join (
select username, max(date) as MaxDate
from MyTable
group by username
) tm on t.username = tm.username and t.date = tm.MaxDate
...
How do I add options to a DropDownList using jQuery?
...lugins,
var myOptions = {
val1 : 'text1',
val2 : 'text2'
};
var mySelect = $('#mySelect');
$.each(myOptions, function(val, text) {
mySelect.append(
$('<option></option>').val(val).html(text)
);
});
If you had lots of options, or this code needed to be run very ...
Get top 1 row of each group
...
;WITH cte AS
(
SELECT *,
ROW_NUMBER() OVER (PARTITION BY DocumentID ORDER BY DateCreated DESC) AS rn
FROM DocumentStatusLogs
)
SELECT *
FROM cte
WHERE rn = 1
If you expect 2 entries per day, then this will arbitrarily pick one...
Select N random elements from a List in C#
I need a quick algorithm to select 5 random elements from a generic list. For example, I'd like to get 5 random elements from a List<string> .
...
How can I convert tabs to spaces in every file of a directory?
...s on each line;
-t 4 means that each tab will be converted to 4 whitespace chars (8 by default).
sponge is from the moreutils package, and avoids clearing the input file.
Finally, you can use gexpand on OSX, after installing coreutils with Homebrew (brew install coreutils).
...
Return rows in random order [duplicate]
...
SELECT * FROM table
ORDER BY NEWID()
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Difference between Select and ConvertAll in C#
...
Select is a LINQ extension method and works on all IEnumerable<T> objects whereas ConvertAll is implemented only by List<T>. The ConvertAll method exists since .NET 2.0 whereas LINQ was introduced with 3.5.
You s...