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oracle行转列
针对oracle数据查询的数据,行转列1.wm_concat函数:例一:select c1,c2,wm_concat(c3) from T where.... group by c1,c2查询结果自动用“,”分割例二:select c1,c2,wm_concat(c3)over(partition ...
分类:数据库   时间:2014-05-10 02:10:46    阅读次数:430
Effective Java 71 Use lazy initialization judiciously
You should initialize most fields normally, not lazily. If you must initialize a field lazily in order to achieve your performance goals, or to break ...
分类:编程语言   时间:2014-05-09 18:32:56    阅读次数:497
What is a heap?--reference
A heap is a partially sorted binary tree. Although a heap is not completely in order, it conforms to a sorting principle: every node has a value less ...
分类:其他好文   时间:2014-05-09 17:34:18    阅读次数:339
Oracle sysdate常用
SELECT * FROM (SELECT * FROM calenderDetail A ORDER BY a. calender desc ) WHERE rownum <3 ;//计算时间大于当前时间的最近2条记录取当前小时,以及相隔一小时v_begin_date:=to_date(to_ch...
分类:数据库   时间:2014-05-09 17:03:41    阅读次数:620
sql 分页row_number() over(order by key)
select * from ( select row_number() over(order by BD008_001) as row ,* from ...
分类:数据库   时间:2014-05-09 16:56:57    阅读次数:328
【LeetCode】Remove Element
题目: Given an array and a value, remove all instances of that value in place and return the new length. The order of elements can be changed. It doesn't matter what you leave beyond the new len...
分类:其他好文   时间:2014-05-05 12:58:57    阅读次数:294
mysql 如何选择随机行
最简单的方式是使用 mysql 的 ORDER BY RAND() 子句。SELECT col1 FROM tbl ORDER BY RAND() LIMIT 10;它能很好的运行在小表中。然而,对于大表,生成随机列表行时将产生一个严重的性能问题,MYSQL 需要对每一行进行随机,然后对它们排序。即...
分类:数据库   时间:2014-05-05 11:04:53    阅读次数:483
LeetCode OJ - Binary Tree Level Order Traversal 1 && 2
BFS以及它的扩展,我发现栈是个很好用的数据结构,特别是对于顺序需要颠倒的时候!!!这里有个重要的信息:可以用null来标识一个level的结束!!!下面是AC代码: 1 /** 2 * Given a binary tree, return the bottom-up level ord...
分类:其他好文   时间:2014-05-05 09:46:06    阅读次数:402
《modern operating system》 chapter 3 MEMORY MANAGEMENT 笔记
Over the years, people discovered the concept of a memory hierarchy,...
分类:其他好文   时间:2014-05-04 09:03:17    阅读次数:247
MVC的Ajax异步请求
@using (Ajax.BeginForm("GetTime","order",new AjaxOptions() { Confirm="你确认这么做吗?", HttpMethod="post", ...
分类:Web程序   时间:2014-05-03 22:50:30    阅读次数:344
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