external_table()external_table()

按名称引用外部表。References an external table by name.

external_table('StormEvent')

语法Syntax

external_table ( TableName [, MappingName ] )external_table ( TableName [, MappingName ] )

参数Arguments

  • TableName:正在查询的外部表的名称。TableName: The name of the external table being queried. 必须是引用 blobadl 类型的外部表的字符串文本。Must be a string literal referencing an external table of kind blob or adl.

  • MappingName:映射对象的可选名称,该对象将实际(外部)数据分片中的字段映射到此函数输出的列。MappingName: An optional name of the mapping object that maps the fields in the actual (external) data shards to the columns output by this function.

备注Notes

有关外部表的详细信息,请参阅外部表See external tables for more information on external tables.

另请参阅用于管理外部表的命令See also commands for managing external tables.

external_table 函数与 table 函数具有类似的限制。The external_table function has similar restrictions as the table function.