1.更改数据库用户名密码： alter user '用户名' identified by ’password'.
2.查看数据库有哪些用户：sqlplus system/password ;select username from dba_users;
3.查看某个用户下有哪些表： select table_name from user_tables;
4.查看表结构：select t.table_name,
t.column_name,
t.data_type,
t.data_length,
t.nullable,
t.column_id,
c.comments,
(SELECT CASE
WHEN t.column_name = m.column_name THEN
1
ELSE
0
END
FROM DUAL) iskey
FROM user_tab_cols t,
user_col_comments c,
(select m.column_name
from user_constraints s, user_cons_columns m
where lower(m.table_name) = 'qh_outstoresabinfo'
and m.table_name = s.table_name
and m.constraint_name = s.constraint_name
and s.constraint_type = 'P') m
WHERE lower(t.table_name) = 'qh_outstoresabinfo'
and c.table_name = t.table_name
and c.column_name = t.column_name
and t.hidden_column = 'NO'
order by t.column_id