In MongoDB, the $rand aggregation pipeline operator returns a random float between 0 and 1.
The floating point value has up to 17 digits after the decimal point. Any trailing zeros are dropped, so the number of digits may vary.
The $rand operator was introduced in MongoDB 4.4.2.
In MongoDB, the $nin query operator selects the documents where the field’s value is not in the specified array or where the field doesn’t exist.
In MongoDB, the $ne aggregation pipeline operator compares two values and returns either true or false, depending on whether the two values are not equivalent.
In MongoDB, the $in aggregation pipeline operator returns a boolean indicating whether a specified value is in the array.
The $in aggregation pipeline operator is not to be confused with the $in query operator, which selects the documents where the value of a field equals any value in the specified array.
In MongoDB, the $in query operator selects the documents where the value of a field equals any value in the specified array.
The $in query operator is not to be confused with the $in aggregation pipeline operator, which returns a boolean indicating whether a specified value is in the array.
If you no longer need a database in MongoDB you can delete it.
Technically speaking, the term normally used for deleting a database is drop. To drop a database is to delete it.
In any case, below are two ways you can drop/delete a database in the mongo shell.
In MongoDB, the $gte aggregation pipeline operator compares two values and returns either true or false, depending on whether or not the first value is greater than or equal to the second value.
In MongoDB, $ifNull is an aggregation pipeline operator that allows you to specify a value to use in place of null.
The way that it works is, you provide an expression and a replacement expression. If the expression evaluates to a non-null value, that expression is returned. But if the expression evaluates to a null value, $ifNull returns the value of the replacement expression.
A null value includes instances of undefined values or missing fields.
In MongoDB, the $gt aggregation pipeline operator compares two values and returns either true or false, depending on whether or not the first value is greater than the second value.
In MongoDB, the $lte aggregation pipeline operator compares two values and returns either true or false, depending on whether or not the first value is less than or equal to the second value.