Question

如果我只使用SELECT SUM语句，我正在使用CASE语句来计算Premium和结果。为什么会这样？

select 
        SUM(CASE WHEN Premium > 0 and Premium <= 5000 AND Year(EffectiveDate)=2016 AND PolicyType = 'New Business' THEN Premium ELSE 0 END) as '0-5K_WP',
        SUM(CASE WHEN Premium > 5000 and Premium <=10000 AND Year(EffectiveDate)=2016 AND PolicyType = 'New Business' THEN Premium ELSE 0 END) AS '5K-10K_WP',
        SUM(CASE WHEN Premium > 10000 and Premium <= 25000 AND Year(EffectiveDate)=2016 AND PolicyType = 'New Business'   THEN Premium ELSE 0 END) AS '10K-25K_WP',
        SUM(CASE WHEN Premium > 25000 and Premium <=50000 AND Year(EffectiveDate)=2016 AND PolicyType = 'New Business'  THEN Premium ELSE 0 END) AS '25K-50K_WP',
        SUM(CASE WHEN Premium > 50000 AND Year(EffectiveDate)=2016 AND PolicyType = 'New Business'  THEN Premium ELSE 0 END) AS '>50K_WP'
FROM    Test_Plaza_ProductionReport 

union all 
select 
        SUM(CASE WHEN Premium > 0 and Premium <= 5000 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) as '0-5K_WP',
        SUM(CASE WHEN Premium > 5000 and Premium <=10000 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) AS '5K-10K_WP',
        SUM(CASE WHEN Premium > 10000 and Premium <= 25000 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) AS '10K-25K_WP',
        SUM(CASE WHEN Premium > 25000 and Premium <=50000 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) AS '25K-50K_WP',
        SUM(CASE WHEN Premium > 50000 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) AS '>50K_WP'
FROM    Test_Plaza_ProductionReport 

union all 
select 

        SUM(CASE WHEN Premium >0 and Premium <= 5000 AND Year(EffectiveDate)=2016 AND  PolicyType = 'Rewrite' THEN Premium ELSE 0 END) as '0-5K_WP',
        SUM(CASE WHEN Premium > 5000 and Premium <=10000 AND Year(EffectiveDate)=2016 AND  PolicyType = 'Rewrite' THEN Premium ELSE 0 END) AS '5K-10K_WP',
        SUM(CASE WHEN Premium > 10000 and Premium <= 25000 AND Year(EffectiveDate)=2016 AND  PolicyType = 'Rewrite' THEN Premium ELSE 0 END) AS '10K-25K_WP',
        SUM(CASE WHEN Premium > 25000 and Premium <=50000 AND Year(EffectiveDate)=2016 AND  PolicyType = 'Rewrite' THEN Premium ELSE 0 END) AS '25K-50K_WP',
        SUM(CASE WHEN Premium > 50000 AND Year(EffectiveDate)=2016 AND  PolicyType = 'Rewrite' THEN Premium ELSE 0 END) AS '>50K_WP'
FROM    Test_Plaza_ProductionReport

总和将 13,286,473 但是现在如果我使用它：

select sum(premium) 
from Test_Plaza_ProductionReport  
where PolicyType in ('New Business','Renewal','Rewrite') 
and Year(EffectiveDate)=2016

现在总和 11,993,445 它的两百万！怎么可能？

Answer 1

您的政策记录中似乎有一些负溢价的记录。在短查询中添加条件以拒绝此类负面溢价记录应该使您的数字匹配。

如果您想考虑负保费，请为他们添加额外的“桶”，即

select 
        SUM(CASE WHEN Premium < 0 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) as 'Negative_WP',
        SUM(CASE WHEN Premium > 0 and Premium <= 5000 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) as '0-5K_WP',
        SUM(CASE WHEN Premium > 5000 and Premium <=10000 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) AS '5K-10K_WP',
        SUM(CASE WHEN Premium > 10000 and Premium <= 25000 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) AS '10K-25K_WP',
        SUM(CASE WHEN Premium > 25000 and Premium <=50000 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) AS '25K-50K_WP',
        SUM(CASE WHEN Premium > 50000 AND Year(EffectiveDate)=2016 AND PolicyType = 'Renewal' THEN Premium ELSE 0 END) AS '>50K_WP'
FROM    Test_Plaza_ProductionReport

Answer 2

您很可能有一个负数，但您的CASE语句仅适用于正数。

运行相同的查询，最后加上额外的谓词溢价＆lt; 0来检查。

Answer 3

为了您的考虑，正如我所提到的，这是一种带有层表的方法。想象一下，定义了多个层，支持大量请求和报告

我们假设您有一个表格层

Tier_Grp      Tier_Title    Tier_R1         Tier_R2
Policy Size   < 0           -999999999.00   0.00
Policy Size   0 - 5K         0.00           5000.00
Policy Size   5K - 10K       5000.00        10000.00
Policy Size   10K - 25K      10000.00       25000.00
Policy Size   25K - 50K      25000.00       50000.00
Policy Size   > 50K          50000.00       999999999.00
Policy Size   Total          -999999999.00  999999999.00

然后通过1个简单查询，您可以获得所有数据，计数，总和，平均值

Select PolicyType
      ,B.Tier_Title
      ,NbrOfPolicies = count(*)
      ,Premium       = sum(Policy)
FROM   Test_Plaza_ProductionReport  A
Join   Tiers on (B.Tier_Grp='Policy Size' and Premium between B.Tier_R1 and B.Tier_R2 and Premium<B.Tier_R2)
Where  Year(EffectiveDate)=2016
Group  By PolicyType
      ,B.Tier_Title  
Order  By PolicyType
      ,B.Tier_R2

为什么使用CASE语句会产生不同的结果？

3 个答案: