1.show current user in oralce
ansower:show user
2.search name of table in current user model.
answer:SELECT table_name FROM user_tables; remember: dictionary user_tables;
3.how to find user by talbe name.
eg.I knows the table name is job_history in oracle.
answer:SELECT owner, table_name FROM dba_tables WHERE table_name IN 'JOB_HISTORY';
NOTE: IN replaced by LIKE.
4.how to use to_date() function in work
eg.SELECT to_date('20171026 22:42:50','yyyy-MM-dd hh24:mi:ss') FROM dual;
NOTE:it can is 12 after in the hh or if can't remeber to_date() format use order by keyword with desc.
5.if oracle database have two instance,you need login special instance.following the command.
eg.instance DBSQL account sys password yangjinhong
sqlplus sys/yangjinhong@DBSQL AS SYSDBA