$lt and $lte for less than in MongoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the $lt operator do in MongoDB?

The $lt operator finds documents where the value of a field is less than a specified value.

beginner

How is $lte different from $lt in MongoDB?

$lte means "less than or equal to" while $lt means strictly "less than". $lte includes the value itself.

beginner

Write a MongoDB query to find all documents where the field age is less than 30.

{ "age": { "$lt": 30 } }

beginner

Write a MongoDB query to find all documents where the field score is less than or equal to 100.

{ "score": { "$lte": 100 } }

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Why would you use $lt or $lte in a real-life database search?

To find items with values below a limit, like products cheaper than $50 ($lt) or students with grades up to 70 ($lte).

Which operator finds documents where a field is strictly less than a value?

A $lte

B $gte

C $gt

D $lt

$lt means less than, excluding the value itself.

What does { "price": { "$lte": 20 } } find?

A Documents with price less than 20

B Documents with price less than or equal to 20

C Documents with price greater than 20

D Documents with price equal to 20 only

$lte means less than or equal to, so prices up to 20 are included.

Which query finds documents where age is less than 18?

A { "age": { "$lt": 18 } }

B { "age": { "$gt": 18 } }

C { "age": { "$gte": 18 } }

D { "age": { "$lte": 18 } }

$lt finds values strictly less than 18.

If you want to include the value 50 in your search for less than or equal, which operator do you use?

A $lte

B $lt

C $gt

D $ne

$lte includes the value itself in the results.

Which operator would NOT be used to find values less than a number?

A $lt

B $lte

C $gt

D tl$

$gt means greater than, so it does not find less than values.

Explain the difference between $lt and $lte in MongoDB queries.

Think about whether the boundary value itself is included or not.

Write a MongoDB query to find all documents where the field temperature is less than or equal to 0.

Use the $lte operator with the field and value.