如何在Oracle数据库的pl/sql过程中存储值

我想在循环迭代后将select查询中的值添加到某个变量/属性中。Java中类似Arraylist的值持有者

循环终止后，我需要删除变量/属性中的值

如何在pl/sql编程中实现这一点

     FOR FEH IN (SELECT ID FROM T_FEH_SG WHERE ZESG_ID IS NOT NULL) LOOP 
     FOR UWBFEH IN (SELECT * FROM T_GRPN_J_FERF WHERE FEH_ID = FEH.ID) LOOP 

     // Here some code to add values from select query based on some conditions


     END LOOP;
      // Here I need to delete the added values.
     END LOOP;

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在这里，如果我删除存储的值，那么这些值也应该从实际表中删除。

我通常建议不要使用嵌套循环，而是使用联接。 在您的示例中，它看起来有点像您希望使用关联数组并用大容量集合填充它：

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由于您实际上不需要t_FEHLERFALL_SG表中的任何数据，因此您只需去掉进行单个选择的第一个循环（使用JOIN、EXISTS或IN，具体取决于您获取的数据）

还有一个重要的问题需要回答-在将数据插入阵列之前，是否需要执行任何逻辑？在清除数组之前，您计划如何处理数组中存储的值

无论如何，这里有一些您可能会觉得有用的选项（另外，我使用了声明的游标，因为它提供了更好的代码可读性，并且据我所知，它由优化器更好地管理，并且可以被重用，可以快速从中获取结果—您还可以阅读关于和的内容）

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您将如何处理这些存储值？另外，如果您绝对必须执行循环游标（又称逐行处理，又称慢对慢）处理，为什么要执行循环嵌套游标？您意识到您刚刚重新发明了嵌套循环联接吗？最好将两个SQL语句合并为一个，让优化器计算出最佳连接路径！

...
TYPE T_myTable IS TABLE OF T_UWB_GRUPPEN_J_FEHLERF%ROWTYPE INDEX BY PLS_INTEGER;
myTable T_myTable;
...
FOR FEH IN (SELECT ID FROM T_FEHLERFALL_SG WHERE ZESG_ID IS NOT NULL) LOOP
   -- select into table
   SELECT * BULK COLLECT INTO myTable FROM T_UWB_GRUPPEN_J_FEHLERF WHERE FEHLERF_ID = FEH.ID;
   ...
   -- delete table
   myTable.DELETE;
END LOOP;
...

DECLARE
    TYPE t_uwbfeh_tab IS TABLE OF T_UWB_GRUPPEN_J_FEHLERF%ROWTYPE INDEX BY PLS_INTEGER; -- empirically learned (and from our DB Oracle consultant) arrays indexed by PL/SQL types (especially PLS_INTEGER) react noticeably faster even for a ~1k-element arrays
    -- declare the PL/SQL TABLE variable and initialize it
    l_uwbfeh_arr t_uwbfeh_tab := NEW t_uwbfeh_tab();

    CURSOR c_fetch_data
    SELECT
        UWBFEH.*
    FROM
        T_FEHLERFALL_SG FEH
        ,T_UWB_GRUPPEN_J_FEHLERF UWBFEH
    WHERE
        FEH.ZESG_ID IS NOT NULL
        AND FEH.ID = UWBFEH.FEHLERF_ID;

BEGIN
    -- If you don't need to do anything with the data in the array before inserting it into the array
    OPEN c_fetch_data;
    FETCH c_fetch_data BULK COLLECT INTO l_uwbfeh_arr;
    CLOSE c_fetch_data;

    -- If you really need to do some logic not doable with the 'smart' select statement
    FOR UWBFEH IN c_fetch_data
    LOOP
        -- extend an array - let it store one more value
        l_uwbfeh_arr.EXTEND;

        -- do some logic with your values (here I just print out the FEHLERF_ID)
        DBMS_OUTPUT.PUT_LINE('FEHLERF_ID: ' || UWBFEH.FEHLERF_ID);

        -- insert the value into the array
        l_uwbfeh_arr(l_uwbfeh_arr.LAST) := UWBFEH;
    END LOOP;

    -- If you need to do something with the data fetched in the array
    IF l_uwbfeh_arr.COUNT > 0 THEN
        FOR idx IN l_uwbfeh_arr.FIRST .. l_uwbfeh_arr.LAST
        LOOP
            -- access the rows as follows (here I just print out the FEHLERF_ID)
            DBMS_OUTPUT.PUT_LINE('FEHLERF_ID: ' || l_uwbfeh_arr(idx).FEHLERF_ID);
        END LOOP;
    END IF;

    -- If you don't actually need any data to be stored in the array and need to manipulate only on the fetched rows
    -- you could skip fetching the data into the array and execute the logic in the following loop
    FOR UWBFEH IN c_fetch_data
    LOOP
        -- here do the logic (here I just print out the FEHLERF_ID)
        DBMS_OUTPUT.PUT_LINE('FEHLERF_ID: ' || UWBFEH.FEHLERF_ID);
    END LOOP;

    -- to delete all the data stored in the array, simply use the following line of code
    l_uwbfeh_arr.DELETE;
END;
/