Question

当前，我们正在使用以下嵌套查询来获取特定结果。该查询为我提供了正确的结果，但是问题在于执行时间更长（大约2秒钟来提取9条记录）。表中的记录：

Table      |  Number of Records
-------------------------------
Account          284
AccountUser       34
AccountCustomer  256
AccountGroup      96

以下是我的查询：

SELECT * FROM Account  where (SomeID = 'XXXXX-XXXXX-XXXXX') and  AccountID  IN  
(SELECT AccountID   FROM AccountUser WHERE SomeID = 'XXXXX-XXXXX-XXXXX' AND AccountID IN  
(SELECT AccountID   FROM AccountCustomer WHERE SomeID = 'XXXXX-XXXXX-XXXXX' AND isDeleted = 0  AND someOtherID IN 
(SELECT someOtherID FROM AccountGroup   WHERE AccountGroupID = 'YYYY-YYYYY-YYYY' AND AccountGroup.SomeID = 'XXXXX-XXXXX-XXXXX' AND AccountID NOT IN  
(SELECT AccountID   FROM AccountGroup WHERE AccountGroupID = 'YYYY-YYYYY-YYYY' AND AccountGroup.SomeID = 'XXXXX-XXXXX-XXXXX'))))

我认为Joins会提供更好的性能（如果我错了，请纠正我），因此将嵌套查询替换为joins，但它没有给我预期的结果。已加入查询，如下所示：

SELECT a.* FROM Account a
Inner join AccountUser b on a.AccountID = b.AccountID
Inner join AccountCustomer c on c.AccountID = a.AccountID 
Inner join AccountGroup d on d.AccountID = a.AccountID 
Inner join AccountGroup e on e.AccountID = a.AccountID 
WHERE a.SomeID = 'XXXXX-XXXXX-XXXXX' and 
      b.SomeID = 'XXXXX-XXXXX-XXXXX' and 
      c.SomeID = 'XXXXX-XXXXX-XXXXX' and 
      c.isDeleted = 0 and d.AccountGroupID = 'YYYY-YYYYY-YYYY' and
      d.SomeID = 'XXXXX-XXXXX-XXXXX' and
      e.AccountGroupID ='YYYY-YYYYY-YYYY'

有人可以告诉我查询中Joins的构造是什么问题。

Answer 1

尝试一下

SELECT distinct a.* FROM Account a
Inner join AccountUser b on a.AccountID = b.AccountID
Inner join AccountCustomer c on c.AccountID = a.AccountID 
Inner join AccountGroup d on d.someOtherID = c.someOtherID 
WHERE a.SomeID = 'XXXXX-XXXXX-XXXXX' and 
      b.SomeID = 'XXXXX-XXXXX-XXXXX' and 
      c.SomeID = 'XXXXX-XXXXX-XXXXX' and 
      c.isDeleted = 0 and d.AccountGroupID = 'YYYY-YYYYY-YYYY' and
      d.SomeID = 'XXXXX-XXXXX-XXXXX' and
      d.AccountID  not in 
(SELECT AccountID   FROM AccountGroup WHERE AccountGroupID = 'YYYY-YYYYY-YYYY' AND AccountGroup.SomeID = 'XXXXX-XXXXX-XXXXX')

Answer 2

我可以找到两个问题。

列名错误

isDeleted = 0更改为c.isRelated = 1
连接d和e的子句错误

AND AccountID NOT

Answer 3

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        showValueSlider.text = String(format: "The value is:%i",Int(sender.value))
    }

应该是

Inner join AccountGroup d on d.AccountID = a.AccountID

？

Answer 4

除了使用JOIN之外，您还可以使用WHERE EXISTS或WHERE NOT EXISTS代替丑陋的IN语句。联接有时可以返回比用IN语句检索的行更多的行。从查询中我看到您只需要帐户表中的数据，所以EXISTS似乎是更合乎逻辑的方法。

我们可以用联接替换嵌套子查询吗-SQL

4 个答案: