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Difference between two dates in MySQL
... value can range from "-838:59:59" to "838:59:59". w3schools.com/SQl/func_mysql_timediff.asp
– cREcker
Aug 3 '17 at 12:21
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MySQL Query GROUP BY day / month / year
...ecord_date), MONTH(record_date)
Check out the date and time functions in MySQL.
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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...
mysql - how many columns is too many?
...tables with many rows, modifying the indexes can take a very long time, as MySQL needs to rebuild all of the indexes in the table. Having the indexes split over several table could make that faster.
Depending on your queries and column types, MySQL could be writing temporary tables (used in more co...
In Java, what is the best way to determine the size of an object?
... Pattern.normalizedPattern (object)
44 4 Node Pattern.root (object)
48 4 Node Pattern.matchRoot (object)
52 4 int[] Pattern.buffer null
56 4 Map Pattern.namedGroups null
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单页web应用（SPA）的简单介绍 - 更多技术 - 清泛网 - 专注C/C++及内核技术
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2.用pushsate记录浏览器的历史，驱动界面发送变化
如何搭建一个基础的SPA
首先，我们画出三个div，它们实际上是作为三个界面存在界面上的，body作为界面外框容器，限制着它们的大小。为了给每个界面配对一个hash地址...
How do I query between two dates using MySQL?
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DATE() is a MySQL function that extracts only the date part of a date or date/time expression
SELECT * FROM table_name WHERE DATE(date_field) BETWEEN '2016-12-01' AND '2016-12-10';
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How do I find which transaction is causing a “Waiting for table metadata lock” state?
...ransactions waiting for locks:
SELECT TRX_ID, TRX_REQUESTED_LOCK_ID, TRX_MYSQL_THREAD_ID, TRX_QUERY
FROM INNODB_TRX
WHERE TRX_STATE = 'LOCK WAIT';
Reference - MySQL Troubleshooting: What To Do When Queries Don't Work, Chapter 6 - Page 96.
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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...
Can someone explain the right way to use SBT?
...use sbt is:
Use sbt-extras - just get the shell script and add it to the root of you project
Create a project folder with a MyProject.scala file for setting up sbt. I much prefer this over the build.sbt approach - it's scala and is more flexible
Create a project/plugins.sbt file and add the approp...