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我们的项目出于测试、演示或者研发自己觉得清爽的原因，经常需要清除数据库中的数据。但是表间定义了大量的外键关联，删除数据还需要遵从一定的业务关系，非常麻烦。我们的小伙伴通常都是Drop user xxx cascade;然后找到初始化脚本重新来过。其实可以在删除表数据之前，先禁用外键约束，删除之后，再启动约束。首先，...

数据泵可以导出dump文件的DDL语句。C:\\Users\\lihuilin>impdp lihuilin/xxxxxx directory=tmp dumpfile=test.dmp sqlfile=test.sqlImport: Release 11.2.0.1.0 - Production on 星期日 11月 10 23:29:50 2013Copyright (c) 1982, 2009, Oracle and/or its affiliates....

Rob, What do you feel like doing tonight? Would you rather play on your PSP, or come with me to a video arcade?If it's OK with you Harry, I would rather stay in and play on my PSP.I was afraid you would say that. Why don't you want to go out?Video arcades are so noisy. And every time I go to one ...

I'm not lazy, but in my free time I don't like playing sports like football because they are so tiring, and I want to relax!I also don't like being with too many people. It's very stressful to go shopping with hundreds of people - and sometimes they can be a bit stupid!I prefer to do something rea...

My best friend really needs a boyfriend - do you know anybody?OK, Tina - let me see....mmmmh....There's John.What's he like?Well, he's very kind and patient.Oh good - she's a really patient person, as well.And he's hardworking...Oh, She isn't so hardworking. Maybe not John, then.OK - Julian i...

单位一个同事误把Exp导入了system帐号，但是系统已经运行了一段时间，数据需要保留，所以不能用源dmp文件重新初始化..解决过程如下1.确定误导入对象的范围2.表的处理3.其他对象的处理4.删除system帐号下误导入的对象初始化对象，并导入system帐号create table t1 as select rownum n from dual connect b...

试验表包括200万记录，其中20万记录是重复的。比较新建表然后改名和原表删除两种去重方法。首先初始化数据。CREATE TABLE test_t (    id NUMBER (8) NOT NULL PRIMARY KEY,    name VARCHAR2 (32) );   ...

用户A执行删除，但是没有提交。SQL> delete from test where object_id

虽然官方不建议建库之后修改字符集，并且修改有一定的限制。但是在测试、演示环境，研发辛辛苦苦建库之后，却发现字符集不符合应用的要求。难道要删除数据库，再重建吗？如果没有应用的数据，则可以使用内部参数修改字符集。实验初始环境字符集是ZHS16GBK，使用内部参数修改为utf8。SQL> select userenv('language') ...

Good afternoon, Ms.Smith. Thank you for coming in today.Good afternoon, please call me Joan.  Thank you for calling me to come in.OK. Let's talk about your experience at your last job.  How long did you work there?I started working there after I graduated, so...for eight years.What dep...

JAVA常用IO方式包括流,通道和MappedByteBuffer。试验通过复制一个大文件（eclipse-jee-juno-SR2-win32.rar 237M）,并选择不同的缓冲区大小，记录复制的时间。影响IO的因素有很多，同样的方式复制时间可能差异很大。所以需要排除一些最大和最小的数据，保证样本的正确性。import java.io.BufferedInputStream;...

外部表使用方式包括数据泵卸载数据，数据泵加载数据和oracle_loader加载数据。首先，需要创建一个Oracle目录SQL> create directory tmp as 'c:\tmp';目录已创建。1.数据泵卸载数据create table t1  (        object_name,object_type,created)    &nbsp...

在Java Web中经常使用缓存，但是如果缓存数据量非常大，则容易出现OOM的情况。可以使用动态代理，限制缓存容器的容量。如果达到容量上限，则可以移除过期的缓存数据。import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;...

如果在程序运行中，需要输出进度等相关信息，可以使用Oracle提供的Pipe功能。首先，创建一个Type。 create or replace type msg as table of varchar2(20) /然后，创建函数create or replace function display (v_count in integer)return msg PIPELINEDasbegin      &...

1.请求长度        RFC对于Get和Post请求并没有长度的限制。        但是浏览器有限制，比如IE浏览器Get请求不能超过2083个字符，而火狐浏览器不能超过65536个字符。浏览器对于Post请求则没有限制。     &n...

首相，创建一张表，只有很少量的记录状态为'N',而我们只需要查询状态为'N'的记录SQL> create table test as select 'Y' flag,o.* from dba_objects o;SQL> update test set flag='N' where rownum<10;已更新9行。SQL> commit;提交完成。然后分别创建函数索引和普通索引SQL> create index inx_flag_n on test(de...

http://blog.csdn.net/tianlesoftware/article/details/5040984set echo offset feedback offset newpage noneset pagesize 5000set linesize 500set verify offset pagesize 0set term offset trims onset linesiz...

s是开始日期，e是结束日期create or replace function workday(s in date,e in date) RETURN INTEGERasresult integer;beginselect count(*) into result from (select to_char(s+level-1,'d') w,s+level-1 from dual connect by level...

1.固定列数create table t1(    studentno int,    subject varchar2(10),    grade int );insert into t1 values(1,'语文',80);insert into t1 values(1,'数学...

给定25个随机数字，要求横向还是纵向，都是由小到大的顺序。public class Data {    int[] data = new int[25];    public Data() {        for (int i = 0; i < 25; i++) {...