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SQL Query to concatenate column values from multiple rows in Oracle
...one is to use LISTAGG:
SELECT pid, LISTAGG(Desc, ' ') WITHIN GROUP (ORDER BY seq) AS description
FROM B GROUP BY pid;
Then join to A to pick out the pids you want.
Note: Out of the box, LISTAGG only works correctly with VARCHAR2 columns.
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How to pass objects to functions in C++?
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Rules of thumb for C++11:
Pass by value, except when
you do not need ownership of the object and a simple alias will do, in which case you pass by const reference,
you must mutate the object, in which case, use pass by a non-const lvalue reference,
you pa...
SQL query to group by day
I want to list all sales, and group the sum by day.
8 Answers
8
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MySQL select one column DISTINCT, with corresponding other columns
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try this query
SELECT ID, FirstName, LastName FROM table GROUP BY(FirstName)
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Are there benefits of passing by pointer over passing by reference in C++?
What are the benefits of passing by pointer over passing by reference in C++?
7 Answers
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data.table vs dplyr: can one do something well the other can't or does poorly?
...m data.table perspective.
Note: unless explicitly mentioned otherwise, by referring to dplyr, we refer to dplyr's data.frame interface whose internals are in C++ using Rcpp.
The data.table syntax is consistent in its form - DT[i, j, by]. To keep i, j and by together is by design. By keeping ...
Oracle “Partition By” Keyword
Can someone please explain what the partition by keyword does and give a simple example of it in action, as well as why one would want to use it? I have a SQL query written by someone else and I'm trying to figure out what it does.
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SQL RANK() versus ROW_NUMBER()
...partition and within that partition the first 3 rows are tied when ordered by ID)
WITH T(StyleID, ID)
AS (SELECT 1,1 UNION ALL
SELECT 1,1 UNION ALL
SELECT 1,1 UNION ALL
SELECT 1,2)
SELECT *,
RANK() OVER(PARTITION BY StyleID ORDER BY ID) AS 'RANK',
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How to use DISTINCT and ORDER BY in same SELECT statement?
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The problem is that the columns used in the ORDER BY aren't specified in the DISTINCT. To do this, you need to use an aggregate function to sort on, and use a GROUP BY to make the DISTINCT work.
Try something like this:
SELECT DISTINCT Category, MAX(CreationDate)
FROM Mon...
How to order by with union in SQL?
... < 15
Union
Select id,name,age
From Student
Where Name like "%a%"
Order by name
the order by is applied to the complete resultset
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