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Is there a MySQL option/feature to track history of changes to records?
I've been asked if I can keep track of the changes to the records in a MySQL database. So when a field has been changed, the old vs new is available and the date this took place. Is there a feature or common technique to do this?
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In MySQL, can I copy one row to insert into the same table?
...o you don't have to worry about the primary key. Setting it to null allows MySQL to choose the value itself, so there's no risk of creating a duplicate.
If you want to be super-sure you're only getting one row to insert, you could add LIMIT 1 to the end of the INSERT INTO line.
Note that I also ap...
How to get database structure in MySQL via query
Is it possible to somehow get structure of MySQL database, or just some table with simple query?
10 Answers
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SQL/mysql - Select distinct/UNIQUE but return all columns?
...ause the behavior on the other columns is unspecified. (The first works in MySQL, if that's what you're using.)
You could fetch the distinct fields and stick to picking a single arbitrary row each time.
On some platforms (e.g. PostgreSQL, Oracle, T-SQL) this can be done directly using window funct...
MySQL Select Date Equal to Today
I'm trying to run a mysql select statement where it looks at today's date and only returns results that signed up on that current day. I've currently tried the following, but it doesn't seem to work.
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MySQL - why not index every field?
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The link is for MS SQL Server; this question is for MySQL
– OMG Ponies
Mar 26 '11 at 23:38
6
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MySQL: how to get the difference between two timestamps in seconds
Is there a way I can make a query in MySQL that will give me the difference between two timestamps in seconds, or would I need to do that in PHP? And if so, how would I go about doing that?
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将Linux代码移植到Windows的简单方法 - 操作系统(内核) - 清泛网 - 专注C/C++及内核技术
...一项困难的工作。本文将以一个实际的例子（Tar）来说明如何把Linux代码移植到Windows平台上。移植过程将尽量少修改代码,以便代码的运行逻辑不会发生任何变动。保留绝大部分软件主要功能。
二．准备工作
Tar是Linux平台下面...
App Inventor 2开发计步器与定位器 - App Inventor 2 中文网 - 清泛IT论坛，有思想、有深度
...编写“健身宝”手机应用程序
3.问题：
（1）如何获取走路步数、距离？
（2）如何计算走路时间？
（3）如何获得当前位置？
（4）如何存储信息？
4.规划：
（1）利用pedometer（计步器）组件...
ALTER TABLE without locking the table?
When doing an ALTER TABLE statement in MySQL, the whole table is read-locked (allowing concurrent reads, but prohibiting concurrent writes) for the duration of the statement. If it's a big table, INSERT or UPDATE statements could be blocked for a looooong time. Is there a way to do a "hot alter", li...