太多行投掷但只选择一行

Question

我有这个过程,它只是根据一个被调用的列字段删除一行AppID.此过程从另一个AppNbr基于该行列调用的列获取值AppID.TOO_MANY_ROWS尝试SELECT连续时,该过程失败并出现异常.这是PL/SQL:

DECLARE
    lvnApplNbr NUMBER;

    PROCEDURE deleteAppl(applId IN VARCHAR2) IS
    BEGIN
        BEGIN
            SELECT ApplNbr -- Exception thrown here
            INTO lvnApplNbr
            FROM Appl
            WHERE ApplID = applId;
        EXCEPTION
            WHEN TOO_MANY_ROWS THEN
                DBMS_OUTPUT.PUT_LINE(SQLERRM);
        END;
        -- ... Delete it after some logic
    END; -- End Procedure
BEGIN
    ...
    deleteAppl('571E00BA-70E6-4523-BEAC-4568C3DD1A7D');
    ...
END;

在TOO_MANY_ROWS当异常被抛出SELECT INTO秒.我不知道为什么它会抛出那个错误,因为如果我只是查询这个:

SELECT ApplNbr FROM Appl WHERE ApplId = '571E00BA-70E6-4523-BEAC-4568C3DD1A7D';

只有一行会回来正确ApplId.

到底是怎么回事？

Answer 1

只需使用相关表(Appl)的别名:

   PROCEDURE deleteAppl(applId IN VARCHAR2) IS
   .....
   .....
   SELECT ApplNbr 
    INTO lvnApplNbr
    FROM Appl a
    WHERE a.ApplID = applId;
   ......

或将您的参数名称(applId)更改为其他名称,例如i_applId:

   PROCEDURE deleteAppl(i_applId IN VARCHAR2) IS
   .....
   .....
   SELECT ApplNbr 
    INTO lvnApplNbr
    FROM Appl
    WHERE ApplID = i_applId;
   ......

因为在你的情况下,多个匹配感知,如果你parameter's name和他们column name是相同的.