Ms access 访问中的左外连接？

以下查询在access中不起作用

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

---

查询表达式中缺少运算符时出错。

在Access中，一次只能联接两个结果。要连接更多表，需要更多括号：

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