Coperator

SELECT LPAD('coperator', 10, '@') "LPAD" FROM DUAL; SELECT RPAD('coperator', 10, '@') "RPAD" FROM DUAL; 输出结果：

ORA-00198: column ambiguously defined ORA-00198: 未明确定义列的错误 解决办法： 寻找不同表中可能相同的字段，加上别名。   ORA-12170: TNS: Connect timeout occurred ORA-12170: TNS: 连接超时 解决办法： 检查网络是否通畅。 1.cmd ping ip地址(要连接的服务器) 2.

SQL> select * from nls_session_parameters;

详细操作步骤： 1.

NVL Syntax Description of the illustration nvl.gif Purpose NVL lets you replace null (returned as a blank) with a string in the results of a query. If expr1 is null, then NVL returns expr

file:///P:/Oracle官方文档/11.2官方文档/server.112/e26088/functions030.htm#SQLRF00617

COUNT Syntax Description of the illustration count.gif See Also: "Analytic Functions" for information on syntax, semantics, and restrictions Purpose COUNT returns the number of rows ret