Filter Expressions

Filter expression is the part of a query which specifies querying condition. A query evaluates data and returns only the subset of data that meets the conditions of the query. Use expressions to filter geospatial data or select a subset of data. For example, you can create an expression that specifies all parcels whose area is larger than 1000 square meters. A query containing this expression displays or selects only parcels that meet those criteria.

General feature query conditions:

Filter is considered empty if it has no filter expressions.
Filter is considered valid if it's not empty and if all of its expressions are valid.
Each filter expression may posses a binary predicate (AND, OR) if used to build an aggregate filter.

A feature query may be:

Simple - when it contains only one filter expression.
Aggregate - when it contains multiple filter expressions (related using logical operators).

Feature filter expressions support following operations:

Filter expressions also support following functions:

Function	Description
Convert()	Converts given expression to a specified object type.
Len()	Returns the length of a specified string.
IsNull()	Tells whether expression resolves to a non-NULL value.
If()	Returns one of the two values depending on the result of a logical expression.
Trim()	Removes all leading and trailing blank characters from string value.
SubString()	Returns a substring from the specified string value.