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Generate GUID in MySQL for existing Data?
I've just imported a bunch of data to a MySQL table and I have a column "GUID" that I want to basically fill down all existing rows with new and unique random GUID's.
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When and why are database joins expensive?
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MySQL, Oracle, SQL Server, Sybase, postgreSQL,etc. care not the order of joins. I've worked with DB2 and it also, to my knowledge, doesn't care what order you put them in. This is not helpful advice in the general case
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how to convert a string to date in mysql?
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As was told at MySQL Using a string column with date text as a date field, you can do
SELECT STR_TO_DATE(yourdatefield, '%m/%d/%Y')
FROM yourtable
You can also handle these date strings in WHERE clauses. For example
SELECT whatever...
How to delete duplicates on a MySQL table?
I need to DELETE duplicated rows for specified sid on a MySQL table.
25 Answers
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MySQL Cannot Add Foreign Key Constraint
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lol same. MySQL could use more precise error handling on this kind of stuff.
– dave
Apr 17 at 23:38
add a comm...
【最全】CSS响应式布局的5种实现方式 - 更多技术 - 清泛网 - 专注C/C++及内核技术
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三、rem 布局
1、rem 如何适配
rem 是相对于 html 根元素的字体大小的单位。
我们通过修改 html 中 font-size 的字体大小来控制 rem 的大小。
比如：
html {
font-size: 10px;
}
.box {
width: 10rem;
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What scalability problems have you encountered using a NoSQL data store? [closed]
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I've switched a small subproject from MySQL to CouchDB, to be able to handle the load. The result was amazing.
About 2 years ago, we've released a self written software on http://www.ubuntuusers.de/ (which is probably the biggest German Linux community website)....
Delete with Join in MySQL
...ect_id = posts.project_id AND projects.client_id = :client_id;
BTW, with mysql using joins is almost always a way faster than subqueries...
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What's the difference between MyISAM and InnoDB? [duplicate]
...c engines you asked about (InnoDB and MyISAM) have different design goals. MySQL also has other storage engines, with their own design goals.
So, in choosing between InnoDB and MyISAM, the first step is in determining if you need the features provided by InnoDB. If not, then MyISAM is up for conside...
mysql check collation of a table
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Works for me in mysql 5.5.52. ...) ENGINE=InnoDB AUTO_INCREMENT=24 DEFAULT CHARSET=latin1 My guess is it may not show the collation if it is set to the default for the database in later versions of mysql/mariadb.
– Deve...