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Simple way to calculate median with MySQL
...the simplest (and hopefully not too slow) way to calculate the median with MySQL? I've used AVG(x) for finding the mean, but I'm having a hard time finding a simple way of calculating the median. For now, I'm returning all the rows to PHP, doing a sort, and then picking the middle row, but surely ...
How to avoid mysql 'Deadlock found when trying to get lock; try restarting transaction'
...AL 900 SECOND
ORDER BY id
) u;
Another thing to keep in mind is that mysql documentation suggest that in case of a deadlock the client should retry automatically. you can add this logic to your client code. (Say, 3 retries on this particular error before giving up).
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When should I use a composite index?
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@felwithe MySQL can only use one index per each of the tables in a query (Exemptions are there. eg, Merging of indexes). Which ideally means that a table in a query, must use a single index for all where-clause, table join, group-by an...
How to refer to relative paths of resources when working with a code repository
.... How do you solve it when you have the following tree structure: /Project_Root_dir /python_files_dir /Some more subdirs here py_file.py /resources /some subdirs here resource_file.csv
– olamundo
Aug 14 '09 at 12...
MYSQL Truncated incorrect DOUBLE value
...ally whenever there is some Syntax issue it throws this useless exception "mysql-truncated-incorrect-double-value"
– heman123
May 10 '18 at 11:47
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MySQL LIKE IN()?
...eing sufficient to give me the correct results, using LIKE as well allowed MySQL to reduce the result set considerably before having to use the slower REGEXP criteria.
– mpen
Feb 15 '12 at 0:11
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SQL Server: SELECT only the rows with MAX(DATE)
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For MySql you can do something like the following:
select OrderNO, PartCode, Quantity from table a
join (select ID, MAX(DateEntered) from table group by OrderNO) b on a.ID = b.ID
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转型产品经理必看 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...文章。创办人人都是产品经理以来，每天都有很多人问我如何转型做产品经理、转型产品经理会遇到哪些问题，其实我一直没能回答好这个问题，因为我从运营转型产品经理的过程太顺利，并且转型的过程也没有做太多的思考和...
Tactics for using PHP in a high-load site
...l you measure and compare your changes.
For example, for many years, the MySQL query cache was the solution to all of our performance problems. If your site was slow, MySQL experts suggested turning the query cache on. It turns out that if you have a high write load, the cache is actually cripplin...
Reading an Excel file in PHP [closed]
... you want to use the data in the excel file. If you want to import it into mysql, you could simply save it as a CSV formatted file and then use fgetcsv to parse it.
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