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How to execute a raw update sql with dynamic binding in rails
...d try accessing the underlying connection and using it's methods, e.g. for MySQL:
st = ActiveRecord::Base.connection.raw_connection.prepare("update table set f1=? where f2=? and f3=?")
st.execute(f1, f2, f3)
st.close
I'm not sure if there are other ramifications to doing this (connections left op...
记一次MongoDB性能问题 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
记一次MongoDB性能问题最近忙着把一个项目从MySQL迁移到MongoDB，在导入旧数据的过程中，遇到了些许波折，犯了不少错误，但同时也学到了不少知识，遂记录下来。公...最近忙着把一个项目从MySQL迁移到MongoDB，在导入旧数据的过...
Why does “_” (underscore) match “-” (hyphen)?
...cluding zero characters).
(From section 3.3.4.7. Pattern Matching in the MySQL documentation.)
If you want to use the underscore in like as a literal, you have to escape it:
select * from a where name like '%taz\_manual%.pdf%';
...
String isNullOrEmpty in Java? [duplicate]
...that when I tried to use StringUtils my IDE (Eclipse) imported it from com.mysql.jdbc.StringUtils which actually has an isNullOrEmpty(myStringObject) method.
ex.
import com.mysql.jdbc.StringUtils;
StringUtils.isNullOrEmpty(host)
Just another alternative for those who already have the MySQL conne...
SQL - Select first 10 rows only?
...
select top 100 * from myTable
select top 100 colA, colB from myTable
In MySQL, use:
select ... order by num desc limit 10
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Node.js vs .Net performance
...ization
nodejs: 228,887
aspnet-stripped: 105,272
Single Query
nodejs-mysql: 88,597
aspnet-stripped-raw: 47,066
Multiple Queries
nodejs-mysql: 8,878
aspnet-stripped-raw: 3,915
Plain Text
nodejs: 289,578
aspnet-stripped: 109,136
In all cases, Node.js tends to be 2x+ faster than IIS.
...
Is there any performance gain in indexing a boolean field?
...e an index, if you have too many records it doesn't use the index anyways.
MySQL not using index when checking = 1 , but using it with = 0
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What is SQL injection? [duplicate]
...d queries, or applying your language/toolkit's escaping functions (such as mysql_real_escape_string() in PHP).
Once you understand SQL Injection you'll get the joke behind this cartoon.
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How to pull a random record using Django's ORM?
...e backend you're using." - any experience on diffrent DB backends? (sqlite/mysql/postgres)?
– kender
Jun 8 '09 at 9:37
4
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How to implement the activity stream in a social network
...s to browse far back in time (if you even offer this)
I use a plain old MySQL table for dealing with about 15 million activities.
It looks something like this:
id
user_id (int)
activity_type (tinyint)
source_id (int)
parent_id (int)
parent_type (tinyint)
time ...