The $where parameter allows you to filter your results using boolean operators. For example, to retrieve only quakes with a magnitude of greater than 3.0:
https://soda.demo.socrata.com/resource/4tka-6guv.json?$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:
https://soda.demo.socrata.com/resource/4tka-6guv.json?$where=magnitude > 3.0 AND source = 'pr'
Multiple boolean operators are available to combine filters:
| Operator | Description | Example |
|---|---|---|
AND |
The logical and of two expressions. | a AND b will return true ONLY if a and b are both true. |
OR |
The logical or of two expressions. | a or b will return true if either a or b are true. |
NOT |
The logical not of an expression. | NOT a will return true, ONLY if a is false. |
IS NULL |
Whether a value is null or not. | a IS NULL will return true, ONLY if a is null. |
IS NOT NULL |
Whether a values is not null. | a IS NOT NULL will return true, ONLY if a is not null |
( ... ) |
Parentheses are used for defining order of operations. | b>3 AND (a=1 OR a=2) |
Note that using simple filtering, equality clauses can be simplified. And since multiple parameters are implicitly ANDed together, the above query can be simplified to:
https://soda.demo.socrata.com/resource/4tka-6guv.json?$where=magnitude > 3.0&source=pr
Multiple equality clauses can be even simpler:
https://soda.demo.socrata.com/resource/4tka-6guv.json?region=Virgin Islands region&source=pr