Therefore, developers have had to learn a new query language for each type of data source or data format that they must support.

因此，开发人员必须针对他们所需支援的资料来源类型或资料格式学习新的查询语言。

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Initializers are typically used in query expressions when they project the source data into a new data type.

初始设定式通常会用在将来源资料规划为新资料型别的查询运算式中。

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If it is not immediately obvious why the error is occurring, examine the query carefully and trace the type of the result of each clause from the data source to the point where the error is occurring.

如果发生此错误的原因不十分明显，请仔细检查查询，并跟踪从数据源到错误发生点的每个子句的结果的类型。

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