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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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How to test if a string is JSON or not?
... with useful data or an error message string produced by the PHP function mysql_error() . How can I test whether this data is a JSON string or the error message.
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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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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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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 ...
File Hash 扩展：文件哈希计算和 Base64 编码文件，sha256、sha512 哈希 ·...
...全文件传输验证
备份文件一致性检查
文件去重比较
密码存储（建议使用加盐哈希）
相关功能
可以使用 Juan Antonio 的 Terminal 扩展 通过 Linux 命令获取文件的 SHA256 哈希：
sha256sum /absolute/path/to/file
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C++特化模板函数的符号多重定义错误问题 - C/C++ - 清泛网 - 专注C/C++及内核技术
....h 中，结果出现特化模板函数的符号多重定义错误。我要如何组织头文件才能避免多重符号定义错误？我用 /FORCE:MULTIPLE，但我想用一个更好的解决方法。
Lee Kyung Jun
实际上，确实用更好的解决方法。稍后我会解释，但首先让我...
Which rows are returned when using LIMIT with OFFSET in MySQL?
...tions%2f10119291%2fwhich-rows-are-returned-when-using-limit-with-offset-in-mysql%23new-answer', 'question_page');
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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...