Question

我在循环中执行了一次获取。如果此提取失败（无数据），我希望CONTINUE循环到EXCEPTION内的下一条记录。

这可能吗？

我得到ORA-06550＆amp; PLS-00201 identifer CONTINUE must be declared

DECLARE
   v_attr char(88);
CURSOR  SELECT_USERS IS
SELECT id FROM USER_TABLE
WHERE USERTYPE = 'X';
BEGIN
    FOR user_rec IN SELECT_USERS LOOP    
        BEGIN
            SELECT attr INTO v_attr 
            FROM ATTRIBUTE_TABLE
            WHERE user_id = user_rec.id;            
         EXCEPTION
            WHEN NO_DATA_FOUND THEN
               -- user does not have attribute, continue loop to next record.
               CONTINUE;
         END;         
    END LOOP;
END;

Answer 1

CONTINUE语句是11g中的新功能。

以下是相关问题：'CONTINUE' keyword in Oracle 10g PL/SQL

Answer 2

在您提供的构造中，您不需要CONTINUE。一旦处理了异常，就会执行END之后的语句，假设您的EXCEPTION块没有终止该过程。换句话说，它将继续进行user_rec循环的下一次迭代。

您还需要在BEGIN块内选择一个变量：

SELECT attr INTO v_attr FROM attribute_table...

显然你必须声明v_attr ......

Answer 3

关于ole goto声明怎么样（我知道，但是它知道，但它在这里工作正常;）

DECLARE
   v_attr char(88);
CURSOR  SELECT_USERS IS
SELECT id FROM USER_TABLE
WHERE USERTYPE = 'X';
BEGIN
    FOR user_rec IN SELECT_USERS LOOP    
        BEGIN
            SELECT attr INTO v_attr 
            FROM ATTRIBUTE_TABLE
            WHERE user_id = user_rec.id;            
         EXCEPTION
            WHEN NO_DATA_FOUND THEN
               -- user does not have attribute, continue loop to next record.
               goto end_loop;
         END;

        <<end_loop>>
        null;         
    END LOOP;
END;

当然，只需将end_loop放在循环的最后。 null可以用提交替代，也可以用计数器增量替换，直到你。

Answer 4

对于这个例子，你真的应该只使用外连接。

declare
begin
  FOR attr_rec IN ( 
    select attr 
    from USER_TABLE u 
    left outer join attribute_table a 
    on ( u.USERTYPE = 'X' and a.user_id = u.id ) 
  ) LOOP
    <process records> 
    <if primary key of attribute_table is null 
     then the attribute does not exist for this user.>
  END LOOP;
END;

Answer 5

Notice you can use WHEN exception THEN NULL the same way as you would use WHEN exception THEN continue. Example:

    DECLARE
        extension_already_exists  EXCEPTION;
        PRAGMA EXCEPTION_INIT(extension_already_exists, -20007);
        l_hidden_col_name  varchar2(32);
    BEGIN
        FOR t IN (  SELECT table_name, cast(extension as varchar2(200)) ext
                    FROM all_stat_extensions
                    WHERE owner='{{ prev_schema }}'
                      and droppable='YES'
                    ORDER BY 1
                 )
        LOOP
            BEGIN
                l_hidden_col_name := dbms_stats.create_extended_stats('{{ schema }}', t.table_name, t.ext);
            EXCEPTION
                WHEN extension_already_exists THEN NULL;   -- ignore exception and go to next loop iteration
            END;
        END LOOP;
    END;

是否可以从异常中继续循环？

5 个答案: