Question

使用11gR2，Windows 7客户端机器。我需要更新表missing_volume（下面），我需要计算estimated_missing列。当前月份的estimate_missing列的计算需要上个月的数字（在下面的代码中注释）。我希望输出像第一个表。请注意记录从1月开始，因此无法计算1月份的estimate_missing，但是对于剩余的月份，可以通过简单地更改“yr”和“mnth”（在代码内部向末尾注释）来完成。 / p>

yr      mnth        location    volume      actual_missing    expected_missing  estimated_missing

2013    January     loc1        48037       24                57                    
2013    February    loc1        47960       3660              53                24
2013    March       loc1        55007       78                57                28
2013    April       loc1        54345       72                58                77

代码：

UPDATE missing_volume g
    SET
        g.estimated_missing = 
        (
            SELECT

                CASE
                    -- If the previous month actual_missing number is less than 2 times than that of the previous month expected_missing number,
                    -- then for current month: 
                    -- estimated_missing = previous_month(actual_missing/volume)*current_month(volume)
                    -- 
                    -- Else, for current month:
                    -- estimated_missing = previous_month(estimated_missing/volume)*current_month(volume)

                    WHEN (NVL(p.actual_missing, 0)/NVL(p.expected_missing, 1)) <= 2.0
                        THEN ROUND(NVL(p.actual_missing, 0)*( NVL(g.volume, 0)/NVL(p.volume, 1) ), 0)
                    ELSE
                        ROUND(NVL(p.estimated_missing, 0)*( NVL(g.volume, 0)/NVL(p.volume, 1) ), 0)
                END                     

            FROM 
                (
                    SELECT
                        yr,
                        mnth,
                        loc_cd,
                        volume,
                        actual_missing,
                        expected_missing,   
                        estimated_missing
                    FROM missing_volume
                    WHERE yr = TRIM(TO_CHAR(ADD_MONTHS(SYSDATE, -2), 'YYYY'))   -- For February it is -4, for March it is -3, for April it is -2
                    AND UPPER(mnth) = UPPER(TRIM(TO_CHAR(ADD_MONTHS(SYSDATE, -2), 'Month')))  -- For February it is -4, for March it is -3, for April it is -2
                )p
            WHERE g.yr = TRIM(TO_CHAR(ADD_MONTHS(SYSDATE, -1), 'YYYY'))   -- For February it is -3, for March it is -2, for April it is -1
            AND UPPER(g.mnth) = UPPER(TRIM(TO_CHAR(ADD_MONTHS(SYSDATE, -1), 'Month')))  -- For February it is -3, for March it is -2, for April it is -1
            AND g.volume IS NOT NULL
            AND TRIM(p.location) = TRIM(g.location)                     
        );

当我运行每个月的代码时，代码确实计算了'estimated_missing'的正确数字，但问题是在更新当前月份时它也会删除上个月的记录。例如。从下面可以看出，在我更新4月之后，该列只有4月的记录，上个月的记录消失了，同样更新3月删除了2月等等。我无法理解为什么会发生这种情况！这是我得到的输出：

yr      mnth        location    volume      actual_missing    expected_missing  estimated_missing

2013    January     loc1        48037       24                57                    
2013    February    loc1        47960       3660              53                
2013    March       loc1        55007       78                57                
2013    April       loc1        54345       72                58                77

如果有任何机构可以解释它为什么会发生（我的意思是代码中的缺陷在哪里）以及如何获得所需的输出（第一个表格），我们将不胜感激。

由于

Answer 1

您需要为语句指定where子句。在WHERE子句里面大括号的那一刻。你的陈述基本上是：

UPDATE missing_volume g
SET
    g.estimated_missing = 
    ( [...]
    ); -- no where clause here

需要的是：

UPDATE missing_volume g
SET
    g.estimated_missing = 
    ( [...]
    )
WHERE g.yr = TRIM(TO_CHAR(ADD_MONTHS(SYSDATE, -1), 'YYYY'));

Haven自己测试过，但这只应该更新当月的行。

代码在更新当前月份记录时删除上个月的记录

1 个答案: