MongoDB How to query for records where field is null or not set

Question

I have an Email document which has a sent at date field        sent at   Date  1336776254000       If this Email has not been sent  the sent at field is either null  or non-existant   I need to get the count of all sent unsent Emails  I m stuck at trying to figure out the right way to query for this information  I think this is the right way to get the sent count   db emails count  sent at    ne  null      But how should I get the count of the ones that aren t sent

User · Accepted Answer

If the sent at field is not there when its not set then   db emails count  sent at    exists  false      If its there and null  or not there at all   db emails count  sent at  null     Refer here for querying and null

User · Answer

Use    db emails count  sent at  null     Which counts all emails whose sent at property is null or is not set  The above query is same as below   db emails count  or       sent at    exists  false       sent at  null

User · Answer

You can also try this   db emails find  and   sent at   exists true   sent at  null    count

User · Answer

db employe find    and     quot dept quot     exists false     quot empno quot      in  101 102           count

User · Answer

If you want to ONLY count the documents with sent at defined with a value of null  don t count the documents with sent at not set    db emails count  sent at     type  10

User · Answer

Seems you can just do single line      sent at   null

[mongodb] MongoDB: How to query for records where field is null or not set?

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