count distinct

To know whether one external_item_key could have more than one subvendorid:

select external_item_key, count(distinct subvendorid)  from dbo.ETL_BULKINSERT_TARGET_HISTORY_POWERSHELL group by external_item_key;

select distinct count(distinct subvendorid)  from dbo.ETL_BULKINSERT_TARGET_HISTORY_POWERSHELL group by external_item_key;

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