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What's the difference between NOT EXISTS vs. NOT IN vs. LEFT JOIN WHERE IS NULL?
...LEFT JOIN / IS NULL: Oracle
NOT IN vs. NOT EXISTS vs. LEFT JOIN / IS NULL: MySQL
In a nutshell:
NOT IN is a little bit different: it never matches if there is but a single NULL in the list.
In MySQL, NOT EXISTS is a little bit less efficient
In SQL Server, LEFT JOIN / IS NULL is less efficient
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First-time database design: am I overengineering? [closed]
...noting that if you're generating CSVs already and want to load them into a mySQL database, LOAD DATA LOCAL INFILE is your best friend: http://dev.mysql.com/doc/refman/5.1/en/load-data.html . Mysqlimport is also worth looking into, and is a command-line tool that's basically a nice wrapper around loa...
淘宝网采用什么技术架构来实现网站高负载的 - 更多技术 - 清泛网 - 专注C/C...
...，淘宝目前也正在从昂贵的高端存储(小型机+ORACLE)切换到MYSQL,切 换到MYSQL以 后，势必会遇到垂直分区(分库)以及水平分区(Sharding)的问题，因此目前淘宝根据自 己的业务特点也开发了自己的TDDL框架，此框架主要解决了分库分表对...
Difference between HBase and Hadoop/HDFS
...d when you have real-time needs.
An analogous comparison would be between MySQL and Ext4.
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How to work around the lack of transactions in MongoDB?
...chnology applied to Mongodb try github.com/Tokutek/mongo , if you need the mysql version maybe they added it to their standard version of Mysql that they usually provide with
– Giovanni Bitliner
Dec 8 '15 at 8:57
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PHP: Convert any string to UTF-8 without knowing the original character set, or at least try
...a pure UTF-8 stack all the way through to your database. I have been using MySQL's utf8mb4 encoding for tables, fields, and connections.
My situation boiled down to "I just want my sanitizers, validators, business logic, and prepared statements to deal with UTF-8 when data comes from HTML forms, or...
Why is SELECT * considered harmful?
...tage of using * is that in some situations it can take better advantage of MySQL's cache systems. If you're running large numbers of similar select queries that request different column names (select A where X,select B where X,...) using a select * where X will allow the cache to handle a larger num...
Can I Replace Apache with Node.js?
I have a website running on CentOS using the usual suspects (Apache, MySQL, and PHP). Since the time this website was originally launched, it has evolved quite a bit and now I'd like to do fancier things with it—namely real-time notifications. From what I've read, Apache handles this poorly. I'm w...
Best way to work with dates in Android SQLite [closed]
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Usually (same as I do in mysql/postgres) I stores dates in int(mysql/post) or text(sqlite) to store them in the timestamp format.
Then I will convert them into Date objects and perform actions based on user TimeZone
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Converting an array of objects to ActiveRecord::Relation
...l as sorting them with a specific column(id for instance). Since I'm using MySQL, the field function could be helpful.
MyModel.where('id in (?)',ids).order("field(id,#{ids.join(",")})")
The SQL looks like:
SELECT ... FROM ... WHERE (id in (11,5,6,7,8,9,10))
ORDER BY field(id,11,5,6,7,8,9,10)
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