Oracle-与过程相关的查询 [英] Oracle - procedure related query

问题描述

我在oracle中编写以下查询:

I am writing the below queries in oracle:

DBMS_OUTPUT .....'Ashish'

DBMS_OUTPUT.....'Ashish'

从tab_1到val1中选择col1

Select col1 into val1 from tab_1

DBMS_OUTPUT .....'Ubale'

DBMS_OUTPUT.....'Ubale'

当我运行此过程时，我只能以"Ashish"的形式得到输出，为什么? 还有v_val1变量的值

when I run this procedure I get the output as "Ashish" only why? also what will be the value of v_val1 variable

注意:该表不包含任何记录

Note: the table does not contain any records

推荐答案

由于表为空，因此"select into"语句将引发NO_DATA_FOUND异常.这就是为什么您没有收到第二条消息的原因. val1将具有与select之前相同的值-即如果您之前未分配值，则为null.

Since the table is empty, the "select into" statement will raise the NO_DATA_FOUND exception. That's why you don't get the second message. val1 will have the same value as before the select - i.e. null if you didn't previously assign a value.

您不知道自己遇到了NO_DATA_FOUND异常，这一事实表明您犯了PL/SQL开发人员有史以来最大的错误之一:

The fact that you don't know you got the NO_DATA_FOUND exception suggests that you have made one of the biggest errors PL/SQL developers ever make:

EXCEPTION
    -- Never do this in real code!!!
   WHEN OTHERS THEN NULL;
END;

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