Question

我需要在＆gt;时提取数据的最大值。 0和最小数据时＆lt; 0.棘手的部分是它应该在同一列中。示例如下：查询下方：

SELECT A.employee_id, paycheck_number
      max ( CASE 
           WHEN B.special = 'XXT' THEN B.AMOUNT
           ELSE 0 
         END ) AMOUNT, 
       max ( CASE 
           WHEN B.special = 'XXH' THEN B.hrs1
           ELSE 0 
         END ) HRS1
FROM   Table1 A, 
       table2 B 
       LEFT OUTER JOIN table3 C 
                    ON B.company = C.company 
WHERE  A .employee_id = '123456789' 
GROUP  BY A.employee_id, paycheck_number 
ORDER  BY 1

返回：

EMPLOYEE_ID   AMOUNT     HRS1     paycheck_number
123456789     2799.82    134.84   1234
123456789     832.86     40       4321
123456789     0          0        5678

如果按数据删除该组，则为：

EMPLOYEE_ID   AMOUNT     HRS1     paycheck_number
123456789     0          134.84   1234
123456789     2799.82    0        1234
123456789     0          40       4321
123456789     832.86     0        4321
123456789     0          -40      5678
123456789     -832.86    0        5678

我想要：

EMPLOYEE_ID   AMOUNT     HRS1     paycheck_number
123456789     2799.82    134.84   1234
123456789     832.86     40       4321
123456789     -832.86    -40      5678

看起来很简单，但是当我尝试时它不起作用。

Answer 1

In Oracle you get the value for the maximum absolute amount via KEEP DENSE_RANK FIRST/LAST:

max(value) keep (dense_rank last order by abs(value))

However, when there is always only the one non-zero value in one record and zeros or nulls in the other records to consider, you could simply add them:

sum(value)

In your case where only one record actually contains a value, you are creating the zero entries yourself and thus get 0 instead of, say, -40 when asking for the maximum value. Remove the ELSE branches that create the interfering zeros, and MAX will get you the correct value. E.g.:

max(case when b.special = 'XXT' then b.amount end) as amount

组BY BY

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