请在oracle告诉我那个nvl [英] please in oracle told me that nvl

问题描述

请告诉我这里发生了什么我的大四学生写了这些代码，但我是oracle的新手所以请告诉我当我们使用nvl时发生了什么

我的代码在这里





string strSelect_Query =SELECT station_id，station_name，station_sys_id，STATION_SCA_ID1，nvl（STATION_SCA_ID2，' - '）STATION_SCA_ID2，nvl（STATION_SCA_ID3，' - '）STATION_SCA_ID3， station_ip，server_ip FROM station_mst;

Please tell me what happened here My senior write these code but i am new in oracle so please tell me what happened when we are using nvl
my code is here


string strSelect_Query = "SELECT station_id,station_name,station_sys_id,STATION_SCA_ID1,nvl(STATION_SCA_ID2,'-')STATION_SCA_ID2,nvl(STATION_SCA_ID3,'-')STATION_SCA_ID3,station_ip,server_ip FROM station_mst";

推荐答案

首先你应该在工作之前接受培训，所以请告诉你的大四。



第二次阅读： http://docs.oracle.com /cd/B19306_01/server.102/b14200/functions105.htm [ ^ ]

First you really should be trained before working, so tell your "senior" that.

Second read this : http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions105.htm[^]

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