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Count the occurrences of DISTINCT values
I am trying to find a MySQL query that will find DISTINCT values in a particular field, count the number of occurrences of that value and then order the results by the count.
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Subqueries vs joins
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Here's an example of how subqueries are evaluated in MySQL 6.0.
The new optimizer will convert this kind of subqueries into joins.
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Why {} + {} is NaN only on the client side? Why not in Node.js?
...as been fixed in Chrome 49.
Very interesting question! Let's dig in.
The root cause
The root of the difference is in how Node.js evaluates these statements vs. how the Chrome development tools do.
What Node.js does
Node.js uses the repl module for this.
From the Node.js REPL source code:
self...
Determine if running on a rooted device
...has a certain piece of functionality that will only work on a device where root is available. Rather than having this feature fail when it is used (and then show an appropriate error message to the user), I'd prefer an ability to silently check if root is available first, and if not,hide the respect...
Count number of files within a directory in Linux? [closed]
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An effective native way without using pipe: du --inodes [root@cs-1-server-01 million]# du --inodes 1000001 ./vdb.1_1.dir 1000003 . [root@cs-1-server-01 million]#
– Venfah Nazir
Jan 9 at 7:28
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修改centos字符集导致桌面进不去的一系列问题 - 更多技术 - 清泛网 - 专注C...
...集请参看 http://user.qzone.qq.com/58740020/blog/1407983208
修改
[root@centos ~]# vi /etc/sysconfig/i18n
发现在终端下ORALCE 可以正常显示汉字
但是centos 不能正常登陆桌面系统，必须手动选择 汉字（中国选项）
但是进入桌面还是UTF-8
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How to export a Vagrant virtual machine to transfer it
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Does the "clean way" account for databases (mySQL, Wordpress) that might be inside the vm? How can that be synced over to the other pc?
– kevllar
Feb 17 '16 at 4:33
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Is storing a delimited list in a database column really that bad?
...ient table-scan. May have to resort to regular expressions, for example in MySQL:
idlist REGEXP '[[:<:]]2[[:>:]]'*
Hard to count elements in the list, or do other aggregate queries.
Hard to join the values to the lookup table they reference.
Hard to fetch the list in sorted order.
To solve th...
Edit the root commit in Git?
...t you have a clean working tree, you can do the following.
# checkout the root commit
git checkout <sha1-of-root>
# amend the commit
git commit --amend
# rebase all the other commits in master onto the amended root
git rebase --onto HEAD HEAD master
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How can the Euclidean distance be calculated with NumPy?
...t(x^2 + y^2 + z^2)) so we're making a lot of sqrt calls. Math 101:
dist = root ( x^2 + y^2 + z^2 )
:.
dist^2 = x^2 + y^2 + z^2
and
sq(N) < sq(M) iff M > N
and
sq(N) > sq(M) iff N > M
and
sq(N) = sq(M) iff N == M
In short: until we actually require the distance in a unit of X rather th...