Question

我有以下查询（在我看来）比它需要的时间太长并且包含可以合并的语句。麻烦的是，我不知道怎么做:)。

我有什么办法可以改善这一点，让它“更好”吗？

SELECT `Date`, `Time`, 

    (SELECT `Buyer Name` 
     FROM [Potential Buyer]
     WHERE `Buyer No` = [Viewing Appointment].`Buyer No`) AS 'Buyer Name',

     (SELECT `Name`
      FROM [Seller] 
      WHERE `Seller No` = (SELECT `Seller No`
                           FROM [Sale Property]
                           WHERE `Property Code` = [Viewing Appointment].`Property Code`)) AS 'Seller Name',

     (SELECT `Address` 
      FROM [Sale Property]
      WHERE `Property Code` = [Viewing Appointment].`Property Code`) AS 'Property Address',

      (SELECT `Name`
       FROM [Staff Member]
       WHERE `Staff ID` = [Viewing Appointment].`Staff Appointed`) AS 'Staff Members Name'

FROM [Viewing Appointment]

此外，目前所选字段的顺序是日期，时间，买方名称，卖方名称，物业地址，员工姓名。无论如何我可以改变这个顺序吗？

感谢。

Answer 1

是的，看看联接

按如下方式重构SQL：

SELECT 
[Viewing Appointment].`Date`, 
[Viewing Appointment].`Time`, 
[Potential Buyer].`Buyer Name`,
Seller.Name,
[Sale Property].Address,
[Staff Member].Name

FROM [Viewing Appointment]

LEFT JOIN [Potential Buyer] ON [Potential Buyer].`Buyer No` = [Viewing Appointment].`Buyer No`
LEFT JOIN [Sale Property].`Property Code` = [Viewing Appointment].`Property Code`
LEFT JOIN Seller ON Seller.`Seller No` = [Sale Property].`Seller No`
LEFT JOIN [Staff Member] ON [Staff Member].`Staff ID` = [Viewing Appointment].`Staff Appointed`

您可以通过以不同的顺序选择字段来更改字段的顺序

如何改进此查询？

1 个答案: