Sql server 将一个表的数据与另一个表的数据进行比较的最佳方法是什么？

我有两个精选语句：

SELECT DISTINCT Email
FROM         dbo.Customers
WHERE     (Email IS NOT NULL) 
AND (Email LIKE '%@%') 
AND (RIGHT(Email, 4) IN ('.net', '.com', '.org')) 
AND (Email NOT LIKE '%@UniformCity.com') 
AND (Email NOT LIKE '%@LifeUniform.com') 
AND (CHARINDEX('.',Email) <> 1)
AND (RIGHT(RTRIM(Email), 1) <> '.') AND (LEFT(LTRIM(Email), 1) <> '@') 
AND (Email not Like '%[`:;_*-,^[^]()+%\/=#-]%' escape '^') order by Email

---

我只想从Customers表中选择不在EmailOptOuts表中的电子邮件。实现这一目标的最佳方式是什么？我考虑过使用游标和循环

绕过清理规则只是为了让下面的代码更干净，您可以这样做：

SELECT c.Email
    FROM dbo.Customers c
    WHERE NOT EXISTS(SELECT NULL
                         FROM [LifeMail].[dbo].[EmailOptOuts] o
                         WHERE c.Email = o.EmailOptOut)

---

您还可以执行以下操作：

SELECT Email     
FROM dbo.Customers      
WHERE Email NOT IN 
    ( SELECT Email                          
      FROM [LifeMail].[dbo].[EmailOptOuts]                          
    ) 

---

我将把这些表放到临时表中，但是如果需要，可以组合查询

SELECT DISTINCT Email
INTO    #tCustomersEmail
FROM    dbo.Customers
WHERE   ( Email IS NOT NULL )
    AND ( Email LIKE '%@%' )
    AND ( RIGHT(Email, 4) IN ( '.net', '.com', '.org' ) )
    AND ( Email NOT LIKE '%@UniformCity.com' )
    AND ( Email NOT LIKE '%@LifeUniform.com' )
    AND ( CHARINDEX('.', Email) <> 1 )
    AND ( RIGHT(RTRIM(Email), 1) <> '.' )
    AND ( LEFT(LTRIM(Email), 1) <> '@' )
    AND ( Email NOT LIKE '%[`:;_*-,^[^]()+%\/=#-]%' ESCAPE '^' )
ORDER BY Email

SELECT  REPLACE(REPLACE(REPLACE(REPLACE(EmailOptOut, '"', ''), ',held', ''),',unsub', ''), ',confirm', '') AS CleanEmail
INTO #tOptOuts
FROM    [LifeMail].[dbo].[EmailOptOuts]

SELECT Email
FROM #tCustomersEmail AS tce
WHERE Email NOT IN (SELECT CleanEmail FROM #tOptOuts AS too)

1个具有左连接的更多解决方案：

SELECT DISTINCT Email
INTO    #tCustomersEmail
FROM    dbo.Customers
WHERE   ( Email IS NOT NULL )
    AND ( Email LIKE '%@%' )
    AND ( RIGHT(Email, 4) IN ( '.net', '.com', '.org' ) )
    AND ( Email NOT LIKE '%@UniformCity.com' )
    AND ( Email NOT LIKE '%@LifeUniform.com' )
    AND ( CHARINDEX('.', Email) <> 1 )
    AND ( RIGHT(RTRIM(Email), 1) <> '.' )
    AND ( LEFT(LTRIM(Email), 1) <> '@' )
    AND ( Email NOT LIKE '%[`:;_*-,^[^]()+%\/=#-]%' ESCAPE '^' )
ORDER BY Email

SELECT  REPLACE(REPLACE(REPLACE(REPLACE(EmailOptOut, '"', ''), ',held', ''),',unsub', ''), ',confirm', '') AS CleanEmail
INTO #tOptOuts
FROM    [LifeMail].[dbo].[EmailOptOuts]

SELECT Email
FROM #tCustomersEmail AS tce
WHERE Email NOT IN (SELECT CleanEmail FROM #tOptOuts AS too)

SELECT Email     
FROM dbo.Customers  c
LEFT JOIN [LifeMail].[dbo].[EmailOptOuts] b ON (b.EmailOptOut = c.Email)
WHERE b.EmailOptOut IS NULL

SELECT qCustomerEmail.Email 
FROM 
    (SELECT DISTINCT Email
    FROM         dbo.Customers
    WHERE     (Email IS NOT NULL) 
    AND (Email LIKE '%@%') 
    AND (RIGHT(Email, 4) IN ('.net', '.com', '.org')) 
    AND (Email NOT LIKE '%@UniformCity.com') 
    AND (Email NOT LIKE '%@LifeUniform.com') 
    AND (CHARINDEX('.',Email) <> 1)
    AND (RIGHT(RTRIM(Email), 1) <> '.') AND (LEFT(LTRIM(Email), 1) <> '@') 
    AND (Email not Like '%[`:;_*-,^[^]()+%\/=#-]%' escape '^')) qCustomerEmail
LEFT JOIN
    (SELECT  replace(replace(
    replace(
    replace(EmailOptOut,'"','')
    , ',held','')
    , ',unsub','')
    , ',confirm','') 
    as CleanEmail
    FROM [LifeMail].[dbo].[EmailOptOuts]) qOptOut
ON qCustomerEmail.Email = qOptOut.CleanEmail
WHERE qOptOut.CleanEmail IS NULL