所以首先要使用[：]符号创建一个空映射。

So first you create an empty map using the [:] notation.

youdao

然而，在V6.1.2或更高版本，这些空元素不再被创建，除非您显式创建了映射。

However, in V6.1.2 and later, these empty elements are no longer created unless you explicitly create a mapping.

youdao

若是创建一个模式来预测将会出现什么数据字段，结果很可能会得到内含大量空字段的表或大量的映射表。

If you were to create a schema to predict what's coming down the pike at you, you'd end up with tables that have lots of empty fields or lots of mapping tables.

youdao