ArcerZhang`s Technology Blog

摘要： Data TypeDescriptionVARCHAR2(size)Variable-length character dataCHAR(size)Fixed-length character dataNUMBER(p,s)Variable-length numeric dataDATEDate and time valuesLONGVariable-length character data(up to 2G);Oracle推荐不使用此数据类型,推荐使用CLOB、BLOBCLOBCharacter data(up to 4GB)RAW and LONG RAWRaw binary dataB 阅读全文

摘要： ObjectivesAfter completing this lesson,you should be able to do the following:Categorize the main database objectsReview the table structureList the data types that are available for columns.Create a simple tableExplain how constraints are created at the time of table creation.Describe how schema ob 阅读全文

摘要： Oracle Database ObjectsObjectDescribtionTableBasic unit of storage;Composed of rowsViewLogically represents subsets of data from one or more tablesSequenceGenerates numeric valuesIndexImporves the performance of some queriesSynonymGives alternative name to an object 阅读全文

摘要： SequencesA sequence:Can automatically generate unique numbersIs a shareable objectCan be used to create a primary key valueReplace application codeSpeeds up the efficiency of accessing sequence values when cached in memory.CREATE SEQUENCE Statement SyntaxDefine a sequence to generate sequential numb 阅读全文

摘要： ObjectivesAfter completing this lesson,you should be able to do the following:Create simple and complex views.Retrieve data from views.Create,maintain,and use sequences.Create and maintain indexes.Create private and public synonyms.Lesson AgendaOverview of views-Creating,modifying,and retrieving dat 阅读全文

摘要： 1、常见问题解决办法:#chmod o=rx /var/ftp2、iptables -t filer -A INPUT -p tcp -m multiport --dport 40000:50000 -j ACCEPT 阅读全文

摘要： 1、cmd下过滤3306端口C:\Users\MaryHu>netstat -an | find /i ":3306" TCP 0.0.0.0:3306 0.0.0.0:0 LISTENING TCP 192.168.1.168:3306 221.182.63.243:1338 FIN_WAIT_1 TCP 192.168.1.168:3306 221.182.63.243:1395 FIN_WAIT_1 阅读全文

摘要： 当今的数据处理大致分为两类：联机事务处理OLTP(on-line transaction processing)、联机分析处理OLAP(on-line Analytical Processing).OLTP是传统的关系型数据库的主要应用，主要是基本的、日常的事务处理，例如银行交易。OLAP是数据仓库系统的主要应用，支持负责的分析操作，侧重决策支持，并且提供直观易懂的查询结果。下面看OLTP和OLAP之间的比较OLTPOLAP用户操作人员，底层管理人员决策人员，高级管理人员功能日常事务处理分析决策DB设计面向应用面向主题数据当前的、最新的细节的、二维的分立的历史的、聚集的、多维的、集成的、统一的 阅读全文

摘要： Objectivesshared pool tune（shared pool 调优）After completing this lesson,you should be able to do the following:Determine the size of an object and pin it in the shared poolTune the shared pool reserved spaceDescribe the user global area (UGA) and session memory considerationsMeasure the library cache 阅读全文

摘要： Thread 1 cannot allocate new log,sequence 1466checkpoint not completecurrent log# 3 seq# 1465 mem#0:/home/ora10g/oradata/ora10g/redo03.log一般情况下，出现上述错误，基本上是由与日志被写满了，所造成的；解决方案：Provide enough groups to prevent waiting. 扩大联机重做日志文件组。 设置联机重做日志的大小. 阅读全文