$and

Compatibility

You can use $and for deployments hosted in the following environments:

• MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

• MongoDB Enterprise: The subscription-based, self-managed version of MongoDB

• MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB

Syntax

The $and has the following syntax:

{ $and: [ { <expression1> }, { <expression2> } , ... , { <expressionN> } ] }

Behavior

When evaluating the clauses in the $and expression, MongoDB's query optimizer considers which indexes are available that could help satisfy clauses of the $and expression when selecting the best plan to execute.

To allow the query engine to optimize queries, $and handles errors as follows:

• If any expression supplied to $and would cause an error when evaluated alone, the $and containing the expression may cause an error but an error is not guaranteed.

• An expression supplied after the first expression supplied to $and may cause an error even if the first expression evaluates to false.

For example, the following query always produces an error if $x is 0:

db.example.find( {
   $expr: { $eq: [ { $divide: [ 1, "$x" ] }, 3 ] }
} )

The following query, which contains multiple expressions supplied to $and, may produce an error if there is any document where $x is 0:

db.example.find( {
   $and: [
      { x: { $ne: 0 } },
      { $expr: { $eq: [ { $divide: [ 1, "$x" ] }, 3 ] } }
   ]
} )

Examples

db.inventory.find( { $and: [ { price: { $ne: 1.99 } }, { price: { $exists: true } } ] } )

db.inventory.find( { price: { $ne: 1.99, $exists: true } } )

db.inventory.find( {
    $and: [
        { $or: [ { qty: { $lt : 10 } }, { qty : { $gt: 50 } } ] },
        { $or: [ { sale: true }, { price : { $lt : 5 } } ] }
    ]
} )