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Difference between float and decimal data type
What difference does it make when I use float and decimal data types in MySQL?.
12 Answers
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UPDATE multiple tables in MySQL using LEFT JOIN
...plete orders: performance of LEFT JOIN compared to NOT IN
Unfortunately, MySQL does not allow using the target table in a subquery in an UPDATE statement, that's why you'll need to stick to less efficient LEFT JOIN syntax.
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NOW() function in PHP
...re a PHP function that returns the date and time in the same format as the MySQL function NOW() ?
20 Answers
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What's the “average” requests per second for a production web application?
...age 200-300 connections per second. Spiking to 800 connections per second.
MySQL handled 2,400 requests per second.
180 Rails instances. Uses Mongrel as the "web" server.
1 MySQL Server (one big 8 core box) and 1 slave. Slave is read only for statistics and reporting.
30+ processes for handling odd ...
Cannot add or update a child row: a foreign key constraint fails
... @SachinfromPune just add SET FOREIGN_KEY_CHECKS=0; at starting of mysql file and SET FOREIGN_KEY_CHECKS=1; at end of mysql file, reimport data
– inrsaurabh
Sep 15 '17 at 12:26
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BIO与NIO、AIO的区别(这个容易理解) - 操作系统(内核) - 清泛网 - 专注C/C++及内核技术
...给OS处理，需要将数据缓冲区地址和大小传给OS(银行卡和密码)，OS需要支持异步IO操作API）；
阻塞 ： ATM排队取款，你只能等待（使用阻塞IO时，Java调用会一直阻塞到读写完成才返回）；
非阻塞 ： 柜台取款，取个号，然后坐在...
Unioning two tables with different number of columns
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Which rows are returned when using LIMIT with OFFSET in MySQL?
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Ordering by the order of values in a SQL IN() clause
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Use MySQL's FIELD() function:
SELECT name, description, ...
FROM ...
WHERE id IN([ids, any order])
ORDER BY FIELD(id, [ids in order])
FIELD() will return the index of the first parameter that is equal to the first parameter (o...
Updating MySQL primary key
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