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MySQL OPTIMIZE all tables?
MySQL has an OPTIMIZE TABLE command which can be used to reclaim unused space in a MySQL install. Is there a way (built-in command or common stored procedure) to run this optimization for every table in the database and/or server install, or is this something you'd have to script up yourself?
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How can I define a composite primary key in SQL?
How can I define a composite primary key consisting of two fields in SQL?
3 Answers
3
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How to Select Every Row Where Column Value is NOT Distinct
...e or be used in an aggregate function error. Is the only fix - editing the sql_mode?
– Volodymyr Bobyr
Jul 16 at 16:21
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Linux 进程卡住了怎么办？ - 操作系统(内核) - 清泛网 - 专注C/C++及内核技术
Linux 进程卡住了怎么办？howto-solve-d-status-process在我们使用 Linux 系统时，如果网络或者磁盘等 I O 出问题，会发现进程卡住了，即使用 kill -9 也无法杀掉进程，很多常用的调试工具，比如 strace, pstack 等也都失灵了
在我们使用...
How to change column datatype in SQL database without losing data
I have SQL Server database and I just realized that I can change the type of one of the columns from int to bool .
11 A...
ActiveRecord.find(array_of_ids), preserving order
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The answer is for mysql only
There is a function in mysql called FIELD()
Here is how you could use it in .find():
>> ids = [100, 1, 6]
=> [100, 1, 6]
>> WordDocument.find(ids).collect(&:id)
=> [1, 6, 100]
>> WordDoc...
How do I escape double quotes in attributes in an XML String in T-SQL?
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tSql escapes a double quote with another double quote. So if you wanted it to be part of your sql string literal you would do this:
declare @xml xml
set @xml = "<transaction><item value=""hi"" /></transaction...
What's the best strategy for unit-testing database-driven applications?
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I'm always running tests against an in-memory DB (HSQLDB or Derby) for these reasons:
It makes you think which data to keep in your test DB and why. Just hauling your production DB into a test system translates to "I have no idea what I'm doing or why and if something break...
SQL Inner-join with 3 tables?
...nthenet.com (my boss recommended it to me, that's how I found it) has good SQL tutorials if you ever have another question and you just want to try and figure it out.
SELECT table1.column1
FROM table1
WHERE table1 > 0 (or whatever you want to specify)
INNER JOIN table1
ON table1.column1 = tabl...
Commenting code in Notepad++
...ng the language manually - or - it contains a mix of languages (eg. inline SQL in Python code), the block comment/uncomment will not work.
– Juha Untinen
Apr 22 '16 at 6:50
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