对于较大的树型数据集，您可能只想加载可见树节点的必要数据，当用户展开一个节点后再记载该节点的子节点。

For large tree data sets you probably want to only load the necessary data for the visible nodes of the tree. When a user expands a node, it starts to load the children of that node.

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例如，如果要绑定到数据集表中的某个列值，则请展开该数据集的名称，然后展开该表名以显示列名。

For example, if you are binding to a column value in a dataset's table, expand the name of the dataset, and then expand the table name to display column names.

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例如，如果要绑定到数据集表中的某个列值，则请展开该数据集的名称，然后展开该表名以显示列名。

For example, if you are binding to a column value in a dataset's table, expand the name of the dataset, and then expand the table name to display column names.

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