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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...
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...
转型产品经理必看 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...文章。创办人人都是产品经理以来，每天都有很多人问我如何转型做产品经理、转型产品经理会遇到哪些问题，其实我一直没能回答好这个问题，因为我从运营转型产品经理的过程太顺利，并且转型的过程也没有做太多的思考和...
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
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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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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...
Multiple queries executed in java in single statement
...BC as it currently provides an exception even though it is possible in the MySQL query browser.
6 Answers
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How to find gaps in sequential numbering in mysql?
... SELECT @var:= max FROM ....; select * from .. WHERE seq < @max; with MySQL variables.
– Moshe L
Mar 25 '19 at 6:08
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MySQL: What's the difference between float and double?
...someone changed a field from float to double. Wondering why, I checked the mysql documentation, but honestly didn't understand what the difference is.
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