Question

我有一个SQL查询，我用它从不同的表中提取数据以获取零件详细信息和装配数据。不幸的是，表格的布局方式似乎需要大量的JOIN。我目前有以下查询，并通过phpmyadmin运行它只显示一个加载屏幕，所以我想它超时，不会在生产中工作。

我在已加入的表和列上添加了索引。我已经通过phpmyadmin对数据库进行了优化，但我仍然难以理解应该如何或可以做到这一点。我是否必须拆分查询并将它们与UNION结合使用？如果是这样的话，我甚至不确定它是如何与它一起工作的，或者它是否有效。

请帮忙。： - ）

EXPLAIN SELECT Import_Values.base_vehicle_id,
    Import_Values.qty,
    Import_Values.part_type_id,
    Import_Values.part_id,
    Import_Values.position_id,
    Import_Values.note,
    Parts.partterminologyname,
    BaseVehicle.YearID,
    Make.MakeName,
    Model.modelname,
    SubModel.SubModelName,
    EngineDesignation.EngineDesignationName,
    EngineVIN.EngineVINName,
    EngineBase.Liter,
    EngineBase.CC,
    EngineBase.CID,
    EngineBase.Cylinders,
    EngineBase.BlockType,
    EngineBase.EngBoreIn,
    EngineBase.EngBoreMetric,
    EngineBase.EngStrokeIn,
    EngineBase.EngStrokeMetric,
    FuelDeliveryType.FuelDeliveryTypeName,
    FuelDeliverySubType.FuelDeliverySubTypeName,
    FuelSystemControlType.FuelSystemControlTypeName,
    FuelSystemDesign.FuelSystemDesignName,
    Aspiration.AspirationName,
    CylinderHeadType.CylinderHeadTypeName,
    FuelType.FuelTypeName,
    IgnitionSystemType.IgnitionSystemTypeName,
    Mfr.MfrName,
    EngineVersion.EngineVersion,
    Valves.ValvesPerEngine,
    BedLength.BedLength,
    BedLength.BedLengthMetric,
    BedType.BedTypeName
    FROM 
    Import_Values
    INNER JOIN BaseVehicle 
        ON Import_Values.base_vehicle_id=BaseVehicle.BaseVehicleID
    INNER JOIN Parts 
        ON Import_Values.part_type_id=Parts.PartTerminologyID
    INNER JOIN Make
        ON BaseVehicle.MakeID=Make.MakeID
    INNER JOIN Model
        ON BaseVehicle.ModelID=Model.ModelID
    INNER JOIN Vehicle
        ON Import_Values.base_vehicle_id=Vehicle.BaseVehicleID
    INNER JOIN SubModel
        ON Vehicle.SubModelID=SubModel.SubModelID
    INNER JOIN VehicleToEngineConfig
        ON Vehicle.VehicleID=VehicleToEngineConfig.VehicleID
    INNER JOIN EngineConfig
        ON VehicleToEngineConfig.EngineConfigID=EngineConfig.EngineConfigID
    INNER JOIN EngineDesignation
        ON EngineConfig.EngineDesignationID=EngineDesignation.EngineDesignationID
    INNER JOIN EngineVIN
        ON EngineConfig.EngineVINID=EngineVIN.EngineVINID
    INNER JOIN EngineBase
        ON EngineConfig.EngineBaseID=EngineBase.EngineBaseID
    INNER JOIN FuelDeliveryConfig
        ON EngineConfig.FuelDeliveryConfigID=FuelDeliveryConfig.FuelDeliveryConfigID
    INNER JOIN FuelDeliveryType
        ON FuelDeliveryConfig.FuelDeliveryTypeID=FuelDeliveryType.FuelDeliveryTypeID
    INNER JOIN FuelDeliverySubType
        ON FuelDeliveryConfig.FuelDeliverySubTypeID=FuelDeliverySubType.FuelDeliverySubTypeID
    INNER JOIN FuelSystemControlType
        ON FuelDeliveryConfig.FuelSystemControlTypeID=FuelSystemControlType.FuelSystemControlTypeID
    INNER JOIN FuelSystemDesign
        ON FuelDeliveryConfig.FuelSystemDesignID=FuelSystemDesign.FuelSystemDesignID
    INNER JOIN Aspiration
        ON EngineConfig.AspirationID=Aspiration.AspirationID
    INNER JOIN CylinderHeadType
        ON EngineConfig.CylinderHeadTypeID=CylinderHeadType.CylinderHeadTypeID
    INNER JOIN FuelType
        ON EngineConfig.FuelTypeID=FuelType.FuelTypeID
    INNER JOIN IgnitionSystemType
        ON EngineConfig.IgnitionSystemTypeID=IgnitionSystemType.IgnitionSystemTypeID
    INNER JOIN Mfr
        ON EngineConfig.EngineMfrID=Mfr.MfrID
    INNER JOIN EngineVersion
        ON EngineConfig.EngineVersionID=EngineVersion.EngineVersionID
    INNER JOIN Valves
        ON EngineConfig.ValvesID=Valves.Valvesid
    INNER JOIN VehicleToBedConfig
        ON Vehicle.VehicleID=VehicleToBedConfig.VehicleID
    INNER JOIN BedConfig
        ON VehicleToBedConfig.BedConfigID=BedConfig.BedConfigID
    INNER JOIN BedLength
        ON BedConfig.BedLengthID=BedLength.BedLengthID
    INNER JOIN BedType
        ON BedConfig.BedTypeID=BedType.BedTypeID

Answer 1

数据库设计很好。这是标准化的一个例子。据我所知，表格和列名称很好。我假设每个表上的id是一个主键，它将有一个索引。查询应该非常快，除非有大量数据（相对于可用内存）。

您的某些表格建议使用多对多关系。一种可能性是查询正在创建一个行的笛卡尔乘积，这些行来自不同维度（在车辆内），这些行乘以行。例如，每辆车可能有多个parts和多个EngineConfig（这纯粹是猜测的例子），因此100个零件和20个配置将产生2,000行。

要进行调试，请从顶部开始，然后解决：

select *
FROM Import_Values INNER JOIN
     BaseVehicle 
     ON Import_Values.base_vehicle_id=BaseVehicle.BaseVehicleID

查看结果并确保您获得了预期的行 - 而不再是。然后继续一次添加一个连接，直到发现问题（性能或行数过多）。

SQL查询 - 大量连接 -

1 个答案: