create table tb2 as select * from emp;alter table tb2 modify empno number(4) not null;翻到20W行 create index idxtb21 on tb2(empno); select INDEX_NAME from dba_indexes where table_name='TB2';--验证index建立起来 set autotrace on; select distinct empno from tb2;
UVA - 10375 Choose and divide Choose and divide Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 4053 Accepted: 1318 Description The binomial coefficient C(m,n) is defined as m! C(m,n) = -------- n!(m-n)! Given four natural numbers p, q
升级到macos sierra xcode8 报提示:requires additional components to support runing and debugging choose Install to add required components 当你遇到这个情况的时候,不要慌.你就是上网搜索也不会有什么好结果的. 本人真实经历该错误,,一小时多解决.该错误的解决可以为开发工程师节省一个小时时间. 亲爱的主耶稣,愿你保守我们. 原因:系统安装完毕自己打开并未重启,须再次重启才能使
What is a high-performance data structure? To answer that question, we're used to applying normal considerations like Big-Oh complexity, and memory overhead, locality, and traversal order. All of those apply to both sequential and concurrent software
笔者最近在使用JSTL标签库的<c:choose>标签时候,发现在该标签体中加了JSP的<!-- -->注释时,总是会显示报错信息.错误的信息如下: <span style="font-size:18px;">org.apache.jasper.JasperException: <h3>Validation error messages from TagLibraryValidator for c in /list.jsp</h3&
from http://www.itpub.net/thread-1852897-1-1.html 有论坛朋友在上面的帖子里问SQL为什么不走索引,正好这两天我也刚刚在看SQL优化,于是试着回答了一下. 下面是原来的SQL: select o.order_id as orderId from order_info o, member mwhere m.member_id = o.member_id and o.is_delete = 'N' /*and (to_date(nvl(o.p
题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=2680 Choose the best route Description One day , Kiki wants to visit one of her friends. As she is liable to carsickness , she wants to arrive at her friend’s home as soon as possible . Now give you a ma
Choose the best route Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 8224 Accepted Submission(s): 2706 Problem Description One day , Kiki wants to visit one of her friends. As she is liable