In MongoDB, the $filter aggregation pipeline operator returns a subset of an array based on a specified condition.
The $filter operator returns an array with only those elements that match the condition, in their original order.
5 Ways to Check the Size of a Collection in MongoDB
In this article I present 5 ways that you can use to check the size of a MongoDB collection when using the mongo shell.
How to Fix “Procedure expects parameter ‘@statement’ of type ‘ntext/nchar/nvarchar’.” Error in SQL Server
It’s quite easy to encounter error Msg 214, Level 16 when executing stored procedures such as sp_executesql or sp_describe_first_result_set.
Fortunately it’s easy to fix too!
The most common reason for getting this error is that you forgot to prefix your string with N.
Therefore, to fix this issue, try prefixing your string with N.
MongoDB $exp
In MongoDB, the $exp aggregation pipeline operator raises Euler’s number (i.e. e ) to the specified exponent and returns the result.
The exponent can be any valid expression that resolves to a number.
MongoDB $tanh
In MongoDB, the $tanh aggregation pipeline operator returns the hyperbolic tangent of a value that is measured in radians.
$tanh accepts any valid expression that resolves to a number.
The $tanh operator was introduced in MongoDB 4.2.
MongoDB $eq Aggregation Pipeline Operator
In MongoDB, the $eq aggregation pipeline operator compares two values and returns either true or false, depending on whether the two values are equivalent or not.
MongoDB $cond
In MongoDB, the $cond aggregation pipeline operator evaluates a boolean expression, and returns one of the two specified return expressions, depending on whether the boolean expression is true or false.
The $cond operator accepts two syntaxes: a longhand syntax and a shorthand syntax. Examples of each are below.
MongoDB $concatArrays
In MongoDB, the $concatArrays aggregation pipeline operator concatenates two or more arrays and returns the concatenated array.
MongoDB $concat
In MongoDB, the $concat aggregation pipeline operator concatenates two or more strings and returns the concatenated string.
MongoDB $cmp
In MongoDB, the $cmp aggregation pipeline operator compares two values and returns either -1, 1, or 0, depending on whether the first value is less than, greater than, or equal to the first value.