The $where Parameter

The $where parameter allows you to filter your results using boolean operators. For example, to retrieve only quakes with a magnitude of greater than 3.0:$where=magnitude > 3.0

You can also combine multiple filters together using boolean operators to chain filters together. If we also only wanted quakes from the pr source:$where=magnitude > 3.0 AND source = 'pr'

Multiple boolean operators are available to combine filters:

Operator Description Example
AND The logical and of two expressions. a AND b will return true ONLY if a and b are both true.
OR The logical or of two expressions. a or b will return true if either a or b are true.
NOT The logical not of an expression. NOT a will return true, ONLY if a is false.
IS NULL Whether a value is null or not. a IS NULL will return true, ONLY if a is null.
IS NOT NULL Whether a values is not null. a IS NOT NULL will return true, ONLY if a is not null
( ... ) Parentheses are used for defining order of operations. b>3 AND (a=1 OR a=2)

Note that using simple filtering, equality clauses can be simplified. And since multiple parameters are implicitly ANDed together, the above query can be simplified to:$where=magnitude > 3.0&source=pr

Multiple equality clauses can be even simpler: Islands region&source=pr