左外连接是否可以访问? [英] Left outer join in access?

问题描述

以下查询在访问中不起作用.

Following query does not work in access.

SELECT Fields.FieldId, PrecisionSettings.DecimalPlaces 

    from Fields left outer join FieldGroup on Fields.FieldGroupId = FieldGroup.FieldGroupId

    left outer join Category on FieldGroup.CategoryId = Category.CategoryId

    left outer join PrecisionSettings on 

    Category.InputAttributesID=PrecisionSettings.AttributesID

它给出错误，因为查询表达式中缺少运算符.

It gives error as missing operator in query expression.

推荐答案

在Access中，一次只能加入两个结果.要连接更多表，您需要更多括号:

In Access you can only join two results at a time. To join more tables you need more parentheses:

SELECT
    Fields.FieldId,
    PrecisionSettings.DecimalPlaces 
FROM
(
    (
        Fields
        LEFT OUTER JOIN FieldGroup ON Fields.FieldGroupId = FieldGroup.FieldGroupId
    )
    LEFT OUTER JOIN Category ON FieldGroup.CategoryId = Category.CategoryId
)
LEFT OUTER JOIN PrecisionSettings ON Category.InputAttributesID = PrecisionSettings.AttributesID

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