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What makes a SQL statement sargable?
...non-sargable is to include a field inside a function in the where clause:
SELECT ... FROM ...
WHERE Year(myDate) = 2008
The SQL optimizer can't use an index on myDate, even if one exists. It will literally have to evaluate this function for every row of the table. Much better to use:
WHERE myDat...
How to take MySQL database backup using MySQL Workbench?
...ble) within Server Administration.
Steps to Create New Server Instance:
Select New Server Instance option within Server Administrator.
Provide connection details.
After creating new server instance , it will be available in Server Administration list. Double click on Server instance you have cr...
支撑Github的开源技术 - 开源 & Github - 清泛网 - 专注C/C++及内核技术
...取服务状态等，在2013年的QCon北京中，Giuthub的工程曾针对如何使用Hubot做运维进行过分享：《ChatOps at GitHub》。
d3
d3是使用JavaScript实现的数据可视化框架，使用HTML、SVG和CSS等，在d3的基础之上发展处诸如crossfilter、NVD3.js等一...
Accessing inactive union member and undefined behavior?
I was under the impression that accessing a union member other than the last one set is UB, but I can't seem to find a solid reference (other than answers claiming it's UB but without any support from the standard).
...
MySQL: determine which database is selected?
After calling mysql_select_db to grab a database, is there any way to later output the name of the database that is currently selected? This seems very basic but I couldn't find anything on php.net or stackoverflow (all results are for "no database selected").
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MySQL “NOT IN” query
...
To use IN, you must have a set, use this syntax instead:
SELECT * FROM Table1 WHERE Table1.principal NOT IN (SELECT principal FROM table2)
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java中的缓存技术该如何实现 - 更多技术 - 清泛网 - 专注C/C++及内核技术
java中的缓存技术该如何实现1缓存为什么要存在?2缓存可以存在于什么地方?3缓存有哪些属性?4缓存介质?搞清楚这4个问题,那么我们就可以随意的通过应用的场景来判断使用何...1、缓存为什么要存在？
2、缓存可以存在于什么地方...
Why shouldn't I use mysql_* functions in PHP?
... 5.5 and above)
$link = mysql_connect('localhost', 'user', 'pass');
mysql_select_db('testdb', $link);
mysql_set_charset('UTF-8', $link);
With PDO: All you need to do is create a new PDO object. The constructor accepts parameters for specifying the database source PDO's constructor mostly takes fo...
C#连接有用户名密码验证的MongoDB - 更多技术 - 清泛网 - 专注C/C++及内核技术
C#连接有用户名密码验证的MongoDBMongoDB连接字符串格式如下：mongodb: [username:password@]hostname[:port][ [database][?options]]使用MongoVUE输入用户名密码能够连接M...MongoDB连接字符串格式如下：mongodb://[username:password@]hostname[:port][/[database][?option...
PHP code to convert a MySQL query to CSV [closed]
...
SELECT * INTO OUTFILE "c:/mydata.csv"
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
LINES TERMINATED BY "\n"
FROM my_table;
(the documentation for this is here: http://dev.mysql.com/doc/refman/5.0/en/select.html)
or:...