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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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#1071 - Specified key was too long; max key length is 1000 bytes
...The INT(1) and INT(32) data types indicates another misunderstanding about MySQL. The numeric argument has no effect related to storage or the range of values allowed for the column. INT is always 4 bytes, and it always allows values from -2147483648 to 2147483647. The numeric argument is about p...
Retrieving the last record in each group - MySQL
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MySQL 8.0 now supports windowing functions, like almost all popular SQL implementations. With this standard syntax, we can write greatest-n-per-group queries:
WITH ranked_messages AS (
SELECT m.*, ROW_NUMBER() OVER (PARTIT...
Cast from VARCHAR to INT - MySQL
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Unsigned is working. From when did MySQL changed Integer datatype to Unsigned?
– Lenin Raj Rajasekaran
Aug 26 '12 at 1:36
20
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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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How to delete from multiple tables in MySQL?
...h out to an EXISTS in 99% of the cases and then there is the 1% where this MySQL syntax takes the day.
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Show MySQL host via SQL Command
...last comment,
I don't think you can resolve IP for the hostname using pure mysql function,
as it require a network lookup, which could be taking long time.
However, mysql document mention this :-
resolveip google.com.sg
docs :- http://dev.mysql.com/doc/refman/5.0/en/resolveip.html
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MySQL - UPDATE query based on SELECT Query
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You can actually do this one of two ways:
MySQL update join syntax:
UPDATE tableA a
INNER JOIN tableB b ON a.name_a = b.name_b
SET validation_check = if(start_dts > end_dts, 'VALID', '')
-- where clause can go here
ANSI SQL syntax:
UPDATE tableA SET validation...
MySQL: selecting rows where a column is null
...E userid = NULL;
This will not give you the expected result, because from mysql doc
In SQL, the NULL value is never true in comparison to any other value, even NULL. An expression that contains NULL always produces a NULL value unless otherwise indicated in the documentation for the operators and ...