1、用户

            查看当前用户的缺省表空间
            SQL>select username,default_tablespace from user_users;

        查看当前用户的角色
        SQL>select * from user_role_privs;

        查看当前用户的系统权限和表级权限
        SQL>select * from user_sys_privs;
        SQL>select * from user_tab_privs;

    2、表

            查看用户下所有的表
            SQL>select * from user_tables;

            查看名称包含log字符的表
            SQL>select object_name,object_id from user_objects
                where instr(object_name,'LOG')>0;

            查看某表的创建时间
            SQL>select object_name,created from user_objects where object_name=upper('&table_name');

            查看某表的大小
            SQL>select sum(bytes)/(1024*1024) as "size(M)" from user_segments
                where segment_name=upper('&table_name');

            查看放在ORACLE的内存区里的表
            SQL>select table_name,cache from user_tables where instr(cache,'Y')>0;

    3、索引

            查看索引个数和类别
            SQL>select index_name,index_type,table_name from user_indexes order by table_name;

            查看索引被索引的字段
            SQL>select * from user_ind_columns where index_name=upper('&index_name');

            查看索引的大小
            SQL>select sum(bytes)/(1024*1024) as "size(M)" from user_segments
                where segment_name=upper('&index_name');

    4、序列号

            查看序列号，last_number是当前值