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How to get next/previous record in MySQL?
...e records with IDs 3,4,7,9 and I want to be able to go from one to another by navigation via next/previous links. The problem is, that I don't know how to fetch record with nearest higher ID.
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SQL Server 2008: How to query all databases sizes?
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I don't know exactly what you mean by efficiency but this is straightforward and it works for me:
SELECT
DB_NAME(db.database_id) DatabaseName,
(CAST(mfrows.RowSize AS FLOAT)*8)/1024 RowSizeMB,
(CAST(mflog.LogSize AS FLOAT)*8)/1024 LogSizeMB,
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Function to Calculate Median in SQL Server
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SELECT AVG(1.0 * val)
FROM (
SELECT val FROM dbo.EvenRows
ORDER BY val
OFFSET (@c - 1) / 2 ROWS
FETCH NEXT 1 + (1 - @c % 2) ROWS ONLY
) AS x;
Of course, just because one test on one schema in 2012 yielded great results, your mileage may vary, especially if you're on SQL Server...
Sorting an array of objects by property values
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Sort homes by price in ascending order:
homes.sort(function(a, b) {
return parseFloat(a.price) - parseFloat(b.price);
});
Or after ES6 version:
homes.sort((a, b) => parseFloat(a.price) - parseFloat(b.price));
Some documenta...
selecting unique values from a column
... DISTINCT operator in MySQL:
SELECT DISTINCT(Date) AS Date FROM buy ORDER BY Date DESC;
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boost Composite keys - C/C++ - 清泛网 - 专注C/C++及内核技术
...lds of a given table. The analogous concept in Boost.MultiIndex is modeled by means of composite_key, as shown in the example:
struct phonebook_entry
{
std::string family_name;
std::string given_name;
std::string phone_number;
phonebook_entry(
std::string family_name,
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How to use SQL Order By statement to sort results case insensitive?
I have a SQLite database that I am trying to sort by Alphabetical order. The problem is, SQLite doesn't seem to consider A=a during sorting, thus I get results like this:
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What is a good pattern for using a Global Mutex in C#?
...turn value in Mutex() constructor call
bool createdNew;
// edited by Jeremy Wiebe to add example of setting up security for multi-user usage
// edited by 'Marc' to work also on localized systems (don't use just "Everyone")
var allowEveryoneRule =
new MutexAccessRule( new Se...
MySQL Orderby a number, Nulls last
Currently I am doing a very basic OrderBy in my statement.
12 Answers
12
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dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
...g summarise with plyr 's ddply function, empty categories are dropped by default. You can change this behavior by adding .drop = FALSE . However, this doesn't work when using summarise with dplyr . Is there another way to keep empty categories in the result?
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