Relationships

A relationship compares any two values and returns a result of true or false.

They can either compare scalar values or spatial geometries.

Scalar Relationships

A scalar relationship compares any two values (boolean, integers, real numbers, dates or strings).

The result is evaluated as true or false, returning true if the values have the specified relationship.

Relationships include equal, not equal, less than, greater than etc., as well as relationships specifically for string: contains, begins with, ends with or matches a regular expression.

Types of Scalar Relationships

Scalar Relationship	Description
Equal	The two values are the same.
Not Equal	The two values are different.
Less Than	The first value is less than the second value.
Less Than or Equal	The first value is less than the second value, or the two values are the same.
Greater Than	The first value is greater than the second value.
Greater Than or Equal	The first value is greater than the second value, or the two values are the same.
Begins With	For string values, test whether the first string begins with the second string.
Ends With	For string values, test whether the first string ends with the second string.
Contains	For string values, test whether the first string contains the second string.
Regular Expression	For string values, check whether the first string matches the wild card string or Perl regular expression in the second string.

Spatial Relationships

A spatial relationship is a type of relationship only applied to geometry values. It returns true if the geometries have the specified relationship.

Any type of geometry can be passed into a spatial relationship check, but only the geometry types relevant to this spatial relationship will be tested. For example, if comparing areas, line geometries will not be tested.

Note: Some spatial relationships can be considered subsets of others. For example, Covered By is a subset of Within (if a geometry is Covered By another geometry, it is also Within that geometry).

The detailed description of each spatial relationship uses the terms interior, boundary, exterior. See Geometries for more information on these terms.

Types of Spatial Relationships

Spatial Relationship	Description
Beyond	Beyond checks that the geometry is at least a certain distance away from another (specified in dataset units). The order of the geometries does not matter. Note: Beyond is the opposite of Within Distance.
Contains	Contain means that the other geometry is completely inside this line or polygon (one object's boundary and interior are inside another). Note: Their boundaries are allowed to intersect, so it includes the Cover and Equal relationships. For lines the boundary means the end points, and for polygons the boundary means all inner and outer rings. The types of geometries that can contain another are: Area contains area Area containsline Area contains point Line contains line Line contains point Point contains point Contains geometries Note: Contains is the reciprocal of Within.
Covered By	Covered By is a special case of Within. It is only true when this geometry is contained within another, and their boundaries intersect (so they share some boundary). For lines the boundary means the end points, and for polygons the boundary means all inner and outer boundary rings. The types of geometries which can be covered by another are: Area covered by area Line covered by area Line covered by line Note: Covered by is the reciprocal of Covers.
Covers	Covers is a special case of Contains. It is only true when the other geometry is contained within this one, and their boundaries intersect (so they share some boundary). For lines the boundary means the end points, and for polygons the boundary means all inner and outer boundary rings. The types of geometries which can cover another are: Area covers area Area covers line Line covers line Note: Covers is the reciprocal of Covered By.
Cross	Two geometries Cross when a line runs across the boundary of an area, or the interior of another line. Note: At least one of the geometries must be a line. The types of geometries which can cross are: Line and line A line crosses another line if only their interiors intersect at single points (and at the same height). Area and line A line crosses a polygon geometry if its interior intersects the polygon’s interior and either of the line’s endpoints are outside the polygon. The order of the geometries does not matter. Cross geometries
Disjoint	Disjoint means that the geometries do not intersect at all (neither the boundaries nor the interiors intersect). The order of the geometries does not matter. Note: Disjoint is the opposite of Intersect.
Equal	Two geometries are Equal when they are identical (they have the same interior, boundary and exterior). Geometries do not need to have the same number of vertices (as long as they follow the same path, within geometric tolerance), and lines do not need to have the same direction. Polygon boundaries do not have to use the same start/end vertex in order to be equal. The order of the geometries does not matter. The types of geometries which can be equal are: Area and area Line and line Point and point Equal geometries
Intersect	Intersect means any sort of spatial interaction. It checks that either the boundaries or interiors of two geometries intersect in any way, using any of the following relationships: Equal Touches Overlap Cross Within Contains The order of the geometries does not matter. Note: Intersect is the opposite of Disjoint.
Overlap	Two geometries Overlap when two lines or two areas partly overlay each other. Overlap means geometries are partly inside and partly outside each other (so does not include being contained or being equal). The types of geometries that can overlap are: Area and area A polygon overlaps another polygon if it shares some but not all of its area. Line and line A line overlaps another line if it shares some but not all of its length. The order of the geometries does not matter. Overlap geometries
Touches	Touch means that the boundaries intersect but the interiors do not. For lines the boundary means the end points, and for polygons the boundary means all inner and outer rings. Adjacent polygons or end-to-end lines touch. The types of geometries that can touch are: Area and area Area and line Area and point Line and line Line and point The order of the geometries does not matter. Touch geometries
Within	Within means this geometry is completely inside the other, which must be a line or polygon. Their boundaries are allowed to intersect, so it includes the Covered by and Equal relationships. For lines the boundary means the end points, and for polygons the boundary means all inner and outer rings. The types of geometries which can be within another are: Area within area Line within area Line within line Point within area Point within line Point within point Within geometries Note: Within is the reciprocal of Contains.
Within Distance	Within Distance checks that the geometries approach within a specified minimum distance of each other (specified in dataset units). The order of the geometries does not matter. Note: Within Distance is the opposite of Beyond.