摘要：十一、replace 替换格式：(原字符串，要查找的字符或字符串，替换的字符或字符串)select replace('hello world','o','a') from dual; //替换时区分大小写select e.empno,replace(e.ename,'S','J') from emp 阅读全文

摘要：一、系统操作cmd->sqlplus / as sysdba; //以管理员身份登录数据库alter user system account unlock; //解锁用户systemalter user scott identified by tiger; //把scott的密码改为tigergra 阅读全文