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SQL select only rows with max value on a column [duplicate]
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I know that MySQL allows you to add non aggregate fields to a "grouped by" query, but I find that kinda pointless. Try running this select id, max(rev), rev from YourTable group by id and you see what I mean. Take your time and try to un...
中关村服务辐射百万创业者 - 资讯 - 清泛网 - 专注C/C++及内核技术
...间、人才、资本……成为拦在创业道路上的种种难题。
如何才能在日益变化的环境下更好地帮到创业者，成为摆在创业服务业面前的最大问题。6月25日，清控科创携手清华控股、北极光创投、完美时空、银杏天使、创业邦、盛...
How to test an SQL Update statement before running it?
...What about Transactions? They have the ROLLBACK-Feature.
@see https://dev.mysql.com/doc/refman/5.0/en/commit.html
For example:
START TRANSACTION;
SELECT * FROM nicetable WHERE somthing=1;
UPDATE nicetable SET nicefield='VALUE' WHERE somthing=1;
SELECT * FROM nicetable WHERE somthing=1; #check
CO...
How do I select an entire row which has the largest ID in the table?
...show profiles and it appears our solutions have the same performance using MySQL. For my own knowledge, do you know what DBMS has poorer performance for subselects?
– unutbu
Feb 7 '14 at 20:08
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How to use JNDI DataSource provided by Tomcat in Spring?
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auth="Container"
type="javax.sql.DataSource"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/TestDB"
username="pankaj"
password="pankaj123"
maxActive="100"
maxIdle="20"
minIdle="5"
maxWait="10000"/>
back to context.xml de spring add this
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Express-js can't GET my static files, why?
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Simply write
app.use(express.static('public/images'));
i.e remove the root directory name in the path. And then you can use the static path effectively in other js files, For example:
<img src="/images/misc/background.jpg">
Hope this helps :)
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How can building a heap be O(n) time complexity?
...n. In particular, this implies that the largest item in the heap is at the root. Sifting down and sifting up are essentially the same operation in opposite directions: move an offending node until it satisfies the heap property:
siftDown swaps a node that is too small with its largest child (thereb...
程序员羊皮卷下载版.pdf - 文档下载 - 清泛网 - 专注C/C++及内核技术
...己
5 安排一次真正的实习，了解社会
5 失败的实习生
6 如何找到适合的实习机会
7 实习成功的三有一无
8 开发人员实习应该这样
9 参加一个社团让自己融入团队
9 承担一份责任
10 感受项目经理的无奈
11 真正感受集体的意...
正则表达式 30 分钟入门教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...：deerchao 转载请注明来源
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Generating Guids in Ruby
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To create a proper, mysql, varchar 32 GUID
SecureRandom.uuid.gsub('-','').upcase
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