Oracle PL/SQL - 使用自定义 SQLERRM 引发用户定义的异常

2021-12-05 00:00:00 exception oracle plsql custom-exceptions

是否可以创建用户定义的异常并能够更改 SQLERRM?

Is it possible to create user-defined exceptions and be able to change the SQLERRM?

例如:

DECLARE
    ex_custom       EXCEPTION;
BEGIN
    RAISE ex_custom;
EXCEPTION
    WHEN ex_custom THEN
        DBMS_OUTPUT.PUT_LINE(SQLERRM);
END;
/

输出是用户定义的异常".是否可以更改该消息?

The output is "User-Defined Exception". Is it possible to change that message?

这里有更多细节.

我希望这能说明我正在努力做得更好.

I hope this one illustrates what I'm trying to do better.

DECLARE
    l_table_status      VARCHAR2(8);
    l_index_status      VARCHAR2(8);
    l_table_name        VARCHAR2(30) := 'TEST';
    l_index_name        VARCHAR2(30) := 'IDX_TEST';
    ex_no_metadata      EXCEPTION;
BEGIN

    BEGIN
        SELECT  STATUS
        INTO    l_table_status
        FROM    USER_TABLES
        WHERE   TABLE_NAME      = l_table_name;
    EXCEPTION
        WHEN NO_DATA_FOUND THEN
            -- raise exception here with message saying
            -- "Table metadata does not exist."
            RAISE ex_no_metadata;
    END;

    BEGIN
        SELECT  STATUS
        INTO    l_index_status
        FROM    USER_INDEXES
        WHERE   INDEX_NAME      = l_index_name;
    EXCEPTION
        WHEN NO_DATA_FOUND THEN
            -- raise exception here with message saying
            -- "Index metadata does not exist."
            RAISE ex_no_metadata;
    END;

EXCEPTION
    WHEN ex_no_metadata THEN
        DBMS_OUTPUT.PUT_LINE('Exception will be handled by handle_no_metadata_exception(SQLERRM) procedure here.');
        DBMS_OUTPUT.PUT_LINE(SQLERRM);
END;
/

实际上，有几十个这样的子块.我想知道是否有一种方法可以为每个子块引发单个用户定义的异常，但让它给出不同的消息，而不是为每个子块创建单独的用户定义的异常.

In reality, there are dozens of those sub-blocks. I'm wondering if there's a way to have a single user-defined exception for each of those sub-blocks to raise, but have it give a different message, instead of creating a separate user-defined exception for each sub-block.

在 .NET 中，这有点像有一个像这样的自定义异常:

In .NET, it would be sort of like having a custom exception like this:

    public class ColorException : Exception
    {
        public ColorException(string message)
            : base(message)
        {
        }
    }

然后，一个方法应该是这样的:

And then, a method would have something like this:

        if (isRed)
        {
            throw new ColorException("Red is not allowed!");
        }

        if (isBlack)
        {
            throw new ColorException("Black is not allowed!");
        }

        if (isBlue)
        {
            throw new ColorException("Blue is not allowed!");
        }

推荐答案

是的.你只需要使用 RAISE_APPLICATION_ERROR 函数.如果您还想为异常命名，则需要使用 EXCEPTION_INIT 编译指示，以便将错误编号与命名异常相关联.类似的东西

Yes. You just have to use the RAISE_APPLICATION_ERROR function. If you also want to name your exception, you'll need to use the EXCEPTION_INIT pragma in order to associate the error number to the named exception. Something like

SQL> ed
Wrote file afiedt.buf

  1  declare
  2    ex_custom EXCEPTION;
  3    PRAGMA EXCEPTION_INIT( ex_custom, -20001 );
  4  begin
  5    raise_application_error( -20001, 'This is a custom error' );
  6  exception
  7    when ex_custom
  8    then
  9      dbms_output.put_line( sqlerrm );
 10* end;
SQL> /
ORA-20001: This is a custom error

PL/SQL procedure successfully completed.

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