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Retrieving the last record in each group - MySQL
...x, we can write greatest-n-per-group queries:
WITH ranked_messages AS (
SELECT m.*, ROW_NUMBER() OVER (PARTITION BY name ORDER BY id DESC) AS rn
FROM messages AS m
)
SELECT * FROM ranked_messages WHERE rn = 1;
Below is the original answer I wrote for this question in 2009:
I write the solu...
What is the purpose of Order By 1 in SQL select statement?
...number stands for the column based on the number of columns defined in the SELECT clause. In the query you provided, it means:
ORDER BY A.PAYMENT_DATE
It's not a recommended practice, because:
It's not obvious/explicit
If the column order changes, the query is still valid so you risk ordering ...
how do i block or restrict special characters from input fields with jquery?
How do I block special characters from being typed into an input field with jquery?
19 Answers
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How can I select rows with most recent timestamp for each key value?
...r data. Each row has a sensor id, a timestamp, and other fields. I want to select a single row with latest timestamp for each sensor, including some of the other fields.
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how to listen to N channels? (dynamic select statement)
...
You can do this using the Select function from the reflect package:
func Select(cases []SelectCase) (chosen int, recv Value, recvOK bool)
Select executes a select operation described by the list of cases. Like
the Go select statement, it bl...
mkdir -p functionality in Python [duplicate]
...rs will fail, in all multitasking operating systems. It's like saying "256 chars should be enough for any path created".
– tzot
Mar 2 '09 at 23:42
4
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SQL query to find record with ID not in another table
...
Try this
SELECT ID, Name
FROM Table1
WHERE ID NOT IN (SELECT ID FROM Table2)
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Count number of records returned by group by
...
You can do both in one query using the OVER clause on another COUNT
select
count(*) RecordsPerGroup,
COUNT(*) OVER () AS TotalRecords
from temptable
group by column_1, column_2, column_3, column_4
share
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must appear in the GROUP BY clause or be used in an aggregate function
...
Yes, this is a common aggregation problem. Before SQL3 (1999), the selected fields must appear in the GROUP BY clause[*].
To workaround this issue, you must calculate the aggregate in a sub-query and then join it with itself to get the additional columns you'd need to show:
SELECT m.cname...
Windbg Step 2 分析程序堆栈实战 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...转载+整理http: www.cnblogs.com killmyday#include"stdafx.h"#include<tchar.h>#ifdef_UNICODE#define_ttol_wtol#else#define_ttolatol#e...转载+整理 http://www.cnblogs.com/killmyday
#include "stdafx.h"
#include <tchar.h>
#ifdef _UNICODE
#define _ttol _wtol
#else
#define _ttol atol
#...