Question

我的表格包含id和两个产品列product和product_other。 product列可能包含有效的产品名称，单词“other”或空白，因为它来自源。如果product_other是“其他”，则product将具有有效的产品名称，否则可能是空白的或随机包含有效的产品名称。我需要将所有有效的产品名称拉到一个列中，并排除空白和“其他”条目。到目前为止，我尝试了两种方法，UNION方法如下：

SELECT DISTINCT * FROM
(
    SELECT id
        , COALESCE(NULLIF(NULLIF(product, 'other'), ''), 'UNKNOWN') AS product
    FROM myTable
    UNION
    SELECT id
        , COALESCE(NULLIF(product_other, ''), 'UNKNOWN') AS product
    FROM myTable
) k
ORDER BY id

这会产生所有行，包括product的'UNKNOWN'值和同一product_other的{{1}}的有效产品名称，当它只提供有效名称时

我使用的另一种方法是下面的id方法：

CASE WHEN

但是，这个列表只生成了有效SELECT id , CASE COALESCE(NULLIF(product, ''), 'UNKNOWN') WHEN 'other' THEN COALESCE(NULLIF(product_other, ''), 'UNKNOWN') ELSE COALESCE(NULLIF(product_other, ''), 'UNKNOWN') END AS product FROM myTable ORDER BY id列表（如果可用）或product product_other为“其他”或空白。它排除了存在有效product 产品和 product_other 值的情况的可能性。

另一种看待它的方法是，如果product查询为k SELECT id, count(*) FROM (，则在第一种情况下会有数量为2的行，无论是否为“UNKNOWN”，以及第二行每) GROUP BY id只有一行。

所以，id看起来像这样：

myTable

我希望查询结果如下所示：

id      product     product_other
------  ---------   ---------------
155535  OTC         COM
155536              OTC
155537  other       COM
155538

感谢。

Answer 1

试试这个：

    CREATE TABLE #temp (id   int ,   product  varchar(10),    product_other VARCHAR(10))


    INSERT INTO #temp 
    VALUES(155535,'OTC','COM'),
    (155536, '' ,'OTC'),
    (155537,'other','COM'),
    (155538,'','') 

SELECT id
    , CASE  WHEN  COALESCE(NULLIF(product, ''),NULLIF(product_other, ''))  = 'other' AND NULLIF(product_other, '') IS NOT NULL  THEN product_other
           WHEN   COALESCE(NULLIF(product, ''),NULLIF(product_other, '')) IS NULL AND  NULLIF(product_other, '') IS NULL  THEN  'UNKNOWN' 
           ELSE  COALESCE(NULLIF(product, ''),NULLIF(product_other, '')) END  AS product 
FROM #temp
UNION
SELECT id
    ,CASE  WHEN  COALESCE(NULLIF(product_other, ''),NULLIF(product, ''))  = 'other' AND NULLIF(product, '') IS NOT NULL  THEN product_other
           WHEN   COALESCE(NULLIF(product_other, ''),NULLIF(product, '')) IS NULL AND  NULLIF(product, '') IS NULL  THEN  'UNKNOWN' 
           ELSE  COALESCE(NULLIF(product_other, ''),NULLIF(product, '')) END  AS product 
FROM #temp;

结果如下：

所以实质上这就是逻辑：

SELECT id
    , CASE  WHEN  COALESCE(NULLIF(product, ''),NULLIF(product_other, ''))  = 'other' AND NULLIF(product_other, '') IS NOT NULL  THEN product_other
           WHEN   COALESCE(NULLIF(product, ''),NULLIF(product_other, '')) IS NULL AND  NULLIF(product_other, '') IS NULL  THEN  'UNKNOWN' 
           ELSE  COALESCE(NULLIF(product, ''),NULLIF(product_other, '')) END  AS product 
FROM myTable
UNION
SELECT id
    ,CASE  WHEN  COALESCE(NULLIF(product_other, ''),NULLIF(product, ''))  = 'other' AND NULLIF(product, '') IS NOT NULL  THEN product_other
           WHEN   COALESCE(NULLIF(product_other, ''),NULLIF(product, '')) IS NULL AND  NULLIF(product, '') IS NULL  THEN  'UNKNOWN' 
           ELSE  COALESCE(NULLIF(product_other, ''),NULLIF(product, '')) END  AS product 
FROM myTable;

Answer 2

SELECT *
FROM myTable
UNPIVOT(product_name FOR product_type IN (product, product_other)) u
WHERE
    u.product_name NOT IN ('', 'other');

SQLFiddle

如何从多列中删除多列并从中排除值？

2 个答案: