更新 WHERE 子句以检查值是否不在单独的表中

Question

我有一个使用WHERE子句的查询，我碰巧在这个表的许多查询中使用了完全相同的WHERE子句（等）。

查询是：

SELECT
    DATENAME(DW, [AtDateTime]) AS [Day of Week]
    ,COUNT(*) AS [Number of Searches]
    ,CAST(CAST(COUNT(*) AS DECIMAL(10, 2)) 
         / COUNT(DISTINCT CONVERT(DATE, [AtDateTime])) AS DECIMAL(10, 2)) 
       AS [Average Searches per Day]
    ,SUM(CASE WHEN [NumFound] = 0 THEN 1 ELSE 0 END) 
       AS [Number of Searches with no Results]
    ,CAST(CAST(SUM(CASE WHEN [NumFound] = 0 THEN 1 ELSE 0 END) 
         AS DECIMAL(10, 2)) / COUNT(*) AS DECIMAL(10, 4)) 
       AS [Percent of Searches with no Results]
FROM [DB].[dbo].[SearchHistory] 
WHERE 
    [CustomerNumber] <> '1234' AND [CustomerNumber] <> '5678'
GROUP BY DATENAME(DW, [AtDateTime]), DATEPART(DW, [AtDateTime])
ORDER BY DATEPART(DW, [AtDateTime])

我希望更改的部分是WHERE子句，而是允许我使用表，这样如果我必须添加要忽略的客户编号，我就不必更新我的所有查询。（并且有相当多的查询具有相同的WHERE子句。）

Answer 1

CREATE TABLE dbo.CustomerExclusions
(
  CustomerNumber VARCHAR(32) PRIMARY KEY -- Is CustomerNumber *really* a string?
);

INSERT dbo.CustomerExclusions(CustomerNumber) VALUES('1234'),('5678');

现在，您WHERE跨所有查询的子句变为：

WHERE NOT EXISTS 
(
  SELECT 1 FROM dbo.CustomerExclusions AS c
  WHERE c.CustomerNumber = SearchHistory.CustomerNumber
)

Answer 2

创建一个表来保存要排除的客户编号，然后NOT EXISTS在WHERE子句中使用 a 排除这些行。

CREATE TABLE dbo.ExcludedCustomers
(
    CustomerNumber VARCHAR(255) NOT NULL
        CONSTRAINT PK_ExcludedCustomers
        PRIMARY KEY CLUSTERED
);

INSERT INTO dbo.ExcludedCustomers (CustomerNumber)
VALUES ('1234')
    , ('5678');


SELECT
    <....>
FROM [DB].[dbo].[SearchHistory] 
WHERE 
    NOT EXISTS (
        SELECT 1
        FROM dbo.ExcludedCustomers ec
        WHERE ec.CustomerNumber = SearchHistory.CustomerNumber
    )
    <...>;