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How to prepend a string to a column value in MySQL?
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Many string update functions in MySQL seems to be working like this:
If one argument is null, then concatenation or other functions return null too.
So, to update a field with null value, first set it to a non-null value, such as ''
For example:
update ta...
Order a MySQL table by two columns
How do I sort a MySQL table by two columns?
5 Answers
5
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...软件过程及其软件产品的跟踪能力。即：怎么命名？版本如何设置？放到哪里？哪些是受控的？受控的级别是什么？读写的权限是什么？
2、配置变更控制
IEEE中的定义：通过建立产品基线，控制软件产品的发布和在整个软件生...
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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