使用LIKE运算符分组并忽略NULL值

Question

我写了一个查询来对税项进行分组,如果税是空的,我不想显示税名.这该怎么做？请检查我的sql server语句:

 SELECT     
   'CENTRAL EXCISE DUTY'    AS 'TaxName',
   SUM(TaxAmount)       AS 'Tax'
 FROM
   PMT_InvoiceTaxAttribute
 WHERE 
   InvoiceID = 100 
   AND TaxAttributeName NOT LIKE '%IBR%' 
   AND TaxAttributeName NOT LIKE '%CST%' 
   AND TaxAttributeName NOT LIKE '%VAT%'
 UNION
 SELECT
   'CST'            AS 'TaxName',
   SUM(TaxAmount)       AS 'Tax'
 FROM
   PMT_InvoiceTaxAttribute
 WHERE 
   InvoiceID = 100   
   AND TaxAttributeName LIKE '%CST%'
 UNION
 SELECT
   'VAT'            AS 'TaxName',
   SUM(TaxAmount)       AS 'Tax'
 FROM
   PMT_InvoiceTaxAttribute
 WHERE 
   InvoiceID = 100   
   AND TaxAttributeName LIKE '%VAT%'

此Query为Output提供如下:

      TaxName                     Tax
   -------------              -----------
  CENTRAL EXCISE DUTY             15000
        CST                       NULL
        VAT                       NULL

在这里,我不想显示CST和VAT,因为它具有空值.

Answer 1

试试这个:

SELECT * FROM (
SELECT     
   'CENTRAL EXCISE DUTY'    AS 'TaxName',
   SUM(TaxAmount)       AS 'Tax'
 FROM
   PMT_InvoiceTaxAttribute
 WHERE 
   InvoiceID = 100 
   AND TaxAttributeName NOT LIKE '%IBR%' 
   AND TaxAttributeName NOT LIKE '%CST%' 
   AND TaxAttributeName NOT LIKE '%VAT%'
 UNION
 SELECT
   'CST'            AS 'TaxName',
   SUM(TaxAmount)       AS 'Tax'
 FROM
   PMT_InvoiceTaxAttribute
 WHERE 
   InvoiceID = 100   
   AND TaxAttributeName LIKE '%CST%'
 UNION
 SELECT
   'VAT'            AS 'TaxName',
   SUM(TaxAmount)       AS 'Tax'
 FROM
   PMT_InvoiceTaxAttribute
 WHERE 
   InvoiceID = 100   
   AND TaxAttributeName LIKE '%VAT%') as SomeName
WHERE TAX is NOT NULL

Answer 2

由于您使用的是SQL Server,因此您可以使用公用表表达式对其进行一些简化,并消除最后不想使用的行HAVING;

WITH cte AS (
  SELECT 
    CASE WHEN TaxAttributeName LIKE '%CST%' THEN 'CST' 
         WHEN TaxAttributeName LIKE '%VAT%' THEN 'VAT'
         WHEN TaxAttributeName LIKE '%IBR%' THEN NULL
         ELSE 'CENTRAL EXCISE DUTY' END TaxName,
    TaxAmount Tax
  FROM PMT_InvoiceTaxAttribute
  WHERE InvoiceID = 100
)
SELECT TaxName, SUM(Tax) Tax FROM cte
GROUP BY TaxName
HAVING TaxName IS NOT NULL AND SUM(Tax) IS NOT NULL

一个要测试的SQLfiddle.

编辑:只是为了完整性,修复现有查询的最小侵入方法是将其包装在另一个删除您不感兴趣的行的选择中;

SELECT * FROM (
    ...your query here...
) a_dummy_name_is_required_here
WHERE Tax IS NOT NULL;

注意对原始查询第一个查询的微小差异,如果行设置为CSTVAT,原有的查询将其视作既CST和VAT,而与CTE的第一个查询会指望它CST而已.我怀疑他们没有重叠,但我想我一定会提到它.