ITPub博客

When you drop a table, the database does not immediately remove the spaceassociated with the table. The database renames the table and places it and anyassociated objects in a recycle bin, where, in case the table was dropped in error, it can be recovered at a later time. This feature is call...

影响Oracle数据库字符集最重要的参数是NLS_LANG参数它的格式如下: NLS_LANG = language_territory.charset它有三个组成部分(语言、地域和字符集)，每个成分控制了NLS子集的特性。其中:Language： 指定服务器消息的语言， 影响提示信息是中文还是英文Territory： 指定服务器的日期和数字格式，Charset：&nb...

The most recent SCN that can be reached with Flashback Database is the current SCN of the database. This query returns the current SCN:SQL> SELECT CURRENT_SCN FROM V$DATABASE;

1引言在关系数据库（DB2，Oracle，Sybase，Informix和SQL Server）最小的恢复和交易单位为一个事务（Transactions）,事务具有ACID(原子性，一致性，隔离性和永久性)特征。关系数据库为了确保并发用户在存取同一数据库对象时的正确性（即无丢失更新、可重复读、不读"脏"数据，无"幻像"读），数据库中引入了并发...

    The most important time model statistic is database time, or DB time Database time represents the total time spent in database calls, and is an indicator of the total instance workload.    DB time只是所有 user response time时间的一部分，如下图所示：&nbsp...