Oracle数据库 FAQs and Tips

　　在已建好的table上添加primary key1.建立索引create　index test_idx on test(id);2.添加?束alter table testadd constraint test_pk primary key (id)using index test_idx;
　　
　　在SQLPLUS中登??出?以下??ERROR:ORA-12638: Credential retrieval failed解?方法:修改sqlnet.ora如果SQLNET.AUTHENTICATION_SERVICES=　(NTS)一行?有被注?,?注?掉#SQLNET.AUTHENTICATION_SERVICES=　(NTS)反之取消注?
　　
　　ALTER SYSTEM SET EVENTS='10231 trace name context forever,level 10' ; 内部事件，设置在全表扫描时跳过损坏的数据块.
　　
　　查看tablespace的空?使用情?select a.tablespace_name, trunc(sum(b.bytes/1024/1024),2) "FREE(M)", trunc(sum(a.bytes/1024/1024)-sum(b.bytes/1024/1024),2) "USED(M)", trunc(sum(a.bytes/1024/1024),2) "ALL(M)", trunc(sum(b.bytes/1024/1024)/sum(a.bytes/1024/1024),2)*100||'%' "Free(%)"from　dba_data_files ajoin　dba_free_space b　on(a.file_id=b.file_id)group by a.tablespace_name;如何指定tnsname.ora的位置?置?境?量TNS_ADMIN
　　
　　?取?前SCN(9i以後)select dbms_flashback.get_system_change_number from dual;

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