In MongoDB, the $switch aggregation pipeline operator evaluates a series of case expressions, and executes a specified expression only when a case expression evaluates to true.
Category: DBMS
Database Management Systems
3 Ways to Remove a Value from an Array in MongoDB
MongoDB provides a few operators that enable you to remove values from arrays.
These include:
$pull$pullAll$pop
MongoDB $mergeObjects
In MongoDB, the $mergeObjects aggregation pipeline operator combines multiple documents into a single document.
2 Ways to Append a Value to an Array in MongoDB
If you have a collection of documents in MongoDB that contain arrays, you can add new values to those arrays if required.
Depending on your specific requirements, you can use the $push operator or the $addToSet operator.
MongoDB $isArray
In MongoDB you can use the $isArray aggregation pipeline operator to check whether or not a value is an array.
It accepts any valid expression, and returns true if the expression is an array, false if it’s not.
MongoDB $literal
In MongoDB, the $literal aggregation pipeline operator returns a value without parsing.
It accepts any valid expression, and returns the unparsed expression.
The $literal operator can be useful for when you have a value that MongoDB could inadvertently interpret as an expression, but you don’t want it to.
For example, if you have a monetary amount that includes a dollar sign, MongoDB might inadvertently interpret that as a field name. You can use $literal to prevent MongoDB from interpreting such expressions.
Return the Partition Number for Each Row When Querying a Partitioned Table in SQL Server (T-SQL)
If you’ve got a partitioned table in SQL Server, and you now want to run a query that includes the partition number on each row returned by the query, you can use the $PARTITION system function to do just that.
The $PARTITION function returns the partition number into which a set of partitioning column values would be mapped for any specified partition function.
You can therefore use it in your SELECT statement to return the partition that each row belongs to.
MongoDB $ln
In MongoDB, the $ln aggregation pipeline operator calculates the natural logarithm (ln) of a number and returns the result as a double.
MongoDB $log
In MongoDB, the $log aggregation pipeline operator calculates the log of a number in the specified base and returns the result as a double.
MongoDB $indexOfCP
In MongoDB, the $indexOfCP aggregation pipeline operator searches a string for an occurrence of a substring and returns the UTF code point index of the first occurrence.
The UTF code point index is zero-based (i.e. it starts at 0).