mysql - Microsoft Access 的 SQL 代码效率和编译问题

Question

有没有一种方法可以更有效地设置此代码？我试图通过几个不同的标准进行过滤，但我什至编译代码都遇到困难。另外，所有 IS NULL 的原因是我想让它在没有输入任何信息的情况下只接受所有数据。

有人对如何优化这段代码有任何建议吗？特别是 WHERE 部分。是否有我可以使用的 if then 语句？还是索引？

SELECT [Table Material Label].Serial, [Table Material Label].[Date Recieved], [Table Material Label].MaterialDescription, [Table Material Label].MaterialCode, [Table Material Label].Supplier, 

[Table Material Label].[Lot Number], [Table Material Label].Weight, [Table Material Label].Quantity, [Table Material Label].[Purchase Order Number], [Table Material Label].[Received By], [Table Material Label].[Checked in By], [Table Material Label].[Total Weight]

FROM [Table Material Label]
WHERE (([Table Material Label].[Date Recieved])>=[Forms]![Report Generator]![Text6] 
    AND ([Table Material Label].[Date Recieved])<=[Forms]![Report Generator]![Text7]) 

    AND ([Table Material Label].MaterialDescription = [Forms]![Report Generator]![repMaterial] 
     OR [Forms]![Report Generator]![repMaterial] IS NULL)

    AND ([Table Material Label].MaterialCode = [Forms]![Report Generator]![repItem] 
     OR [Forms]![Report Generator]![repItem] IS NULL)

    AND ([Table Material Label].[Lot Number] = [Forms]![Report Generator]![repLot] 
     OR [Forms]![Report Generator]![repLot] IS NULL)

    AND ([Table Material Label].Weight = [Forms]![Report Generator]![repWeight] 
     OR [Forms]![Report Generator]![repWeight] IS NULL)

    AND ([Table Material Label].Quantity = [Forms]![Report Generator]![repQuantity] 
     OR [Forms]![Report Generator]![RepQuantity] IS NULL)

    AND ([Table Material Label].[Purchase Order Number] = [Forms]![Report Generator]![repPurchaseOrder] 
     OR [Forms]![Report Generator]![repPurchaseOrder] IS NULL)

    AND ([Table Material Label].[Received By] = [Forms]![Report Generator]![repRecBy] 
     OR [Forms]![Report Generator]![repRecBy] IS NULL)

    AND ([Table Material Label].[Checked in By] = [Forms]![Report Generator]![repCheckBy] 
     OR [Forms]![Report Generator]![repCheckBy] IS NULL)

    AND ([Table Material Label].[Total Weight] = [Forms]![Report Generator]![repTotalWeight] 
     OR [Forms]![Report Generator]![repTotalWeight] IS NULL)

    AND ([Table Material Label].Supplier = [Forms]![Report Generator]![Supp] 
     OR [Forms]![Report Generator]![Supp] IS NULL)


ORDER BY [Table Material Label].[Date Recieved], [Table Material Label].MaterialDescription, [Table Material Label].MaterialCode, [Table Material Label].Supplier;

Answer 1

您的 WHERE 代码最简单，至少我不知道任何更简单的解决方案。每个条件有两个条件，如果您需要显示空条件的所有记录，这是最低限度。此代码只有一个问题 - 您应该将查询保留为 SQL 文本格式。如果你切换到查询生成器，它会变得一团糟，几乎无法阅读。由于 SQL 文本并不复杂，因此运行此查询不会有任何问题，它不会被编译。当然，您应该为 WHERE 子句中的每个字段建立索引，以获得更好的性能。