Extracting _sent data view from parent business unit via SQL query not returning all records

Question

I am trying to extract _Sent data view records in a data extension via SQL query from the parent / enterprise business unit in SFMC.

When I am running this query (expectation is that extracted data will include parent BU + all child BUs)

Getting: 30millions records (expected)

Select 
AccountID,
OYBAccountID,
JobID,
ListID,
BatchID,
SubscriberID,
SubscriberKey,
EventDate,
Domain,
TriggererSendDefinitionObjectID,
TriggeredSendCustomerKey
FROM _Sent WITH (NOLOCK)

When I am running this query with excluding one business unit (expectation is that extracted data will include parent BU + all child BUs minus one child business unit)

Getting: 8millions records (expected is 10millionos)

Select 
AccountID,
OYBAccountID,
JobID,
ListID,
BatchID,
SubscriberID,
SubscriberKey,
EventDate,
Domain,
TriggererSendDefinitionObjectID,
TriggeredSendCustomerKey
FROM _Sent WITH (NOLOCK)
WHERE 
OYBAccountID != 1234567

In second query I am also not seeing parent BU records. My understanding is that in _Sent log, parent BU records do not have OYBAccountID field populated, is that accurate?

Is there any issue with my query how I am using NOT equal to? I have tried both != AND <> - same results (missing data)

Please advise?

Answer 1

If you want exclude specific BU, then use this SQL snippet below to accommodate Parent BU's NULL value for the OYBAccountID column.

ISNULL(OYBAccountID, 0) != 1234567