oracle同一实例不同用户之间所有对象的数据导入
同一实例下,不同用户之间的数据同步导入
1,exp from a user,imp to b user,
2,impdp network_link,不生成dump文件直接导入
…
flashback drop table,index is recovery?
For a table to be recoverable using Flashback Drop, it must reside in a locally managed tablespace. Also, tables in the SYSTEM tablespaces cannot recovered using Flashback Drop regardless of the tablespace type.
ORACLE DBMS_TDS
Transportable tablespace feature introduced since Oracle 10g allowed a tablespace placed in a read only mode to be transported to another database and plugged in. However system and sysaux tablespaces were not transportable
oracle initrans and maxtrans
In earlier releases of Oracle Database, the MAXTRANS parameter limited the number of transaction entries that could concurrently use data in a data block. This parameter has been deprecated.
oracle 删除not null非空约束
system@ORCL> create table testnull(id int not null,name varchar2(10) not null);
Table created.
oracle grant update a column on table(给一列授权update)
oracle 10 允许 基于表中某一列单独授权 update 权限
anbob@ORCL> conn system
Enter password:
alter table rename talblename、columnname、indexname、constraintsname
重命名表名、字段名、索引名、约束名
SQL> CREATE TABLE test1 (
2 col1 NUMBER(10) NOT NULL,
3 col2 VARCHAR2(50) NOT NULL);
…….
oracle 修改列的前后顺序
Whether you are create table or alter table plus a filling, the column is asequence of before and after,In oracle you can modify the sequence.
for example: