Question

我尝试在过程未插入记录时引发异常。我的代码如下：

CREATE OR REPLACE PROCEDURE OPEN_CLASS(
    p_class IN TUTPRAC.CLASSID%TYPE,
    p_unitc IN TUTPRAC.UNITCODE%TYPE,
    p_classd IN TUTPRAC.CLASS_DAY%TYPE,
    p_classt IN TUTPRAC.CLASS_TIME%TYPE,
    p_classtp IN TUTPRAC.CLASS_TYPE%TYPE,
    p_roomnm IN TUTPRAC.ROOMNUM%TYPE)
IS
    -- Variables    
    x number:=0;
    y number:=0;  
    CLASS_CLASH EXCEPTION;
BEGIN
    -- checks
    SELECT nvl((SELECT 1 
                FROM TUTPRAC
                 WHERE UNITCODE = p_unitc and CLASS_DAY = p_classd 
                  or CLASS_DAY = p_classd and CLASS_TIME = p_classt
                  and ROOMNUM = p_roomnm) , 0) 
    INTO x FROM dual;
    SELECT nvl((SELECT 1 
                FROM UNITSTREAM 
                WHERE UNITCODE = p_unitc and DAY = p_classd 
                or DAY = p_classd and TIME = p_classt 
                and LOCATION = p_roomnm) , 0) 
    INTO y FROM dual;
    -- insert
    IF (x = 0 and y = 0) THEN
      INSERT INTO TUTPRAC (CLASSID, UNITCODE, CLASS_DAY, CLASS_TIME, CLASS_TYPE, ROOMNUM) 
      VALUES (p_class, p_unitc, p_classd, p_classt, p_classtp, p_roomnm);
    ELSE
      RAISE CLASS_CLASH;
    END IF;
EXCEPTION
      WHEN CLASS_CLASH THEN
        DBMS_OUTPUT.PUT_LINE('Record was not inserted due to a class clash.');
END OPEN_CLASS;

当我运行此程序时，如果记录没有任何碰撞，则显示PL/SQL procedure successfully completed.并在表中添加记录。问题是，即使它发现冲突并且没有添加记录，它仍然会说出相同的消息，而不是我异常的输出。

Answer 1

由于您在程序中捕获了异常 - 该过程不会异常终止。所以，public static class Board { private static Square[] gameBoard = new Square[56]; static public void SetUpBoard() { for (int i = 1; i == 55; i++) { gameBoard[i] = new Square("Ordinary Square", i); } gameBoard[0] = new Square("Start", 0); gameBoard[4] = new Square.Lose_Square("Lose Square", 4); gameBoard[5] = new Square.Chance_Square("Chance Square", 5); gameBoard[9] = new Square.Win_Square("Win Square", 9); gameBoard[11] = new Square.Chance_Square("Chance Square", 11); gameBoard[14] = new Square.Lose_Square("Lose Square", 14); gameBoard[17] = new Square.Chance_Square("Chance Square", 17); gameBoard[19] = new Square.Win_Square("Win Square", 19); gameBoard[24] = new Square.Lose_Square("Lose Square", 24); gameBoard[29] = new Square.Win_Square("Win Square", 29); gameBoard[34] = new Square.Lose_Square("Lose Square", 34); gameBoard[35] = new Square.Chance_Square("Chance Square", 35); gameBoard[39] = new Square.Win_Square("Win Square", 39); gameBoard[44] = new Square.Lose_Square("Lose Square", 44); gameBoard[47] = new Square.Chance_Square("Chance Square", 47); gameBoard[49] = new Square.Win_Square("Win Square", 49); gameBoard[53] = new Square.Chance_Square("Chance Square", 53); gameBoard[55] = new Square("Finish", 56); } public static Square GetGameBoardSquare(int n) { Square S = new Square(); S = gameBoard[n]; return S; } public static Square StartSquare() { return gameBoard[0]; } public static Square NextSquare(int n) { return gameBoard[(n+1)]; } }是正确的输出。要使您的过程抛出异常，您需要在EXCEPTION块中发出PL/SQL procedure successfully completed.。

如果由于raise;输出被抑制，您可能看不到此消息。如果您将DBMS_OUTPUT作为程序的第一行，请检查是否看到任何输出。如果您没有 - 请在调用您的程序之前检查您是否在sqlplus会话中调用DBMS_OUTPUT.put_line。

Answer 2

您可能没有在会话中执行set serveroutput on。

您的代码将引发异常，找不到数据。我认为您期望在没有匹配项时使用NULL，因此您已使用NVL。但是select语句不会返回任何内容，而不是您期望的NULL。

这是没有发现数据异常的原因。

您可以使用count(*) into x和count(*) into y代替NVL。它应该可以正常工作。

PLSQL EXCEPTION不起作用

2 个答案: