Difference between $in and $or

[Mariana_45491 (Mariana Kova)]

Dear colleagues,
can anyone explain please on the example the difference between $in and $or operators, since I don’t see any difference in practice so far.
Thanks in advance

[kanikasingla]

Hi Mariana_45491,

First, $in is a comparison operator and $or operator is a logical operator. And let me try to put in simple words, you use $in when you want 2 possible values on the same field.
$or when you want any one of the conditions to be true and it does not have to be on the same field.

Consider one collection: movies and here are 2 example documents:

Consider these 2 queries:

1. You want year either 1895 or 1897, so you can do this with any of these 2 queries:

   > db.movies.find( { year: { $in: [1895,1897] } } )
   

   OR

   db.movies.find( { $or: [ {year: 1895}, {year:1897} ] } } )

   The output will be same.

2. You want either year either 1895 or viewerVotes > 100, so you can do this with $or:

    > db.movies.find( { $or: [ { year: 1895 }, { viewerVotes: { $gt: 100 } } ] } )
   

   You cannot do this with $in operator.

For more details, you can always refer mongodb docs

Kanika

[Mariana_45491 (Mariana Kova)]

I exactly had first case that is why was confused. Thank you very much for illustrative examples!