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MySQL: Transactions vs Locking Tables
...is transferred. And the bank's account, into which they'll happily deposit all the service fees charged on the transaction. Given (as everyone knows these days) that banks are extraordinarily stupid, let's say their system works like this:
$balance = "GET BALANCE FROM your ACCOUNT";
if ($balance &l...
Using a dispatch_once singleton model in Swift
...variables), and is thread safe by the definition of let. This is now officially recommended way to instantiate a singleton.
Class constants were introduced in Swift 1.2. If you need to support an earlier version of Swift, use the nested struct approach below or a global constant.
Nested struct
cl...
SQL query return data from multiple tables
...I-89 syntax (and if you are used to 89, may seem much less intuitive - but all I can say is to try it) as it is much easier to understand when the queries start getting more complex. Why use it? Is there a performance gain? The short answer is no, but it is easier to read once you get used to it. It...
How to recover a dropped stash in Git?
... review yesterday's stashed changes, but git stash pop appears to remove all references to the associated commit.
19 Answ...
关于我们 · App Inventor 2 中文网，少儿编程陪伴者
...员中心 中文社区 关于 var _hmt = _hmt || []; (function() { var hm = document.createElement("script"); hm.src = "https://hm.baidu.com/hm.js?8d287b854d737bdc880e8ddeac1b309d"; var s = document.getElementsByTagName("script")[0]; s.parentNod...
Remove specific commit
...hanged line 2"
1 files changed, 1 insertions(+), 1 deletions(-)
Then it all works as expected.
The second answer was very interesting. There is a feature which has not yet been officially released (though it is available in Git v1.7.2-rc2) called Revert Strategy. You can invoke git like this:
...
How to generate a random string in Ruby
...).chr }.join
I spend too much time golfing.
(0...50).map { ('a'..'z').to_a[rand(26)] }.join
And a last one that's even more confusing, but more flexible and wastes fewer cycles:
o = [('a'..'z'), ('A'..'Z')].map(&:to_a).flatten
string = (0...50).map { o[rand(o.length)] }.join
...
Understanding how recursive functions work
...mming question which I have just not been able to grok yet. Filtering out all of the (extremely clever) "In order to understand recursion, you must first understand recursion." replies from various online threads I still am not quite getting it.
...
SQL Server indexes - ascending or descending, what difference does it make?
...ces to rows.
Since the table is clustered, the references to rows are actually the values of the pk. They are also ordered within each value of col1.
This means that that leaves of the index are actually ordered on (col1, pk), and this query:
SELECT col1, pk
FROM mytable
ORDER BY
col1...
Vim: Creating parent directories on save
...ries for files like ftp://* and !isdirectory will prevent expensive mkdir call.
Update: sligtly better solution that also checks for non-empty buftype and uses mkdir():
function s:MkNonExDir(file, buf)
if empty(getbufvar(a:buf, '&buftype')) && a:file!~#'\v^\w+\:\/'
let dir=...