Object Relationships

There are several different types of relationship between objects in InfoAsset Manager. Each type of relationship provides a particular behaviour to represent the connection between the object types.

The different types of relationships (built-in and user defined) are described below:

Relationship type	Description
Simple Relationship	A simple relationship relates one object type to another object type. For example a valve survey object may be related to a valve, or a pump may be part of a pump station.
Asset Relationship	An asset relationship represents the situation where an object type may be related to a number of specified objects types (usually Assets). For example a general survey object may be related to any asset type, a property or a zone.
All Node Relationship	An all node relationship allows an object to be related to a node of any type in the network. For example a pipe has two node relationships – an upstream node relationship (US node ID) and a downstream node relationship (DS node ID).
All Link Relationship	An all link relationship allows an object to be related to a link of any type in the network.
Collection Network Pipe Relationships	Pipes in Collection networks are treated slightly differently to other object types, since they are identified differently from other types (they use US node ID,DS node ID and Link suffix fields). This means that relationships to pipe objects need to be treated as a special case. As a result, pipes in collection networks cannot be used a part of an asset relationship. For example, CCTV surveys are related to surveyed pipes using the pipe fields mentioned above.

Relationships can exist for many different reasons. For example, one object type may be a component of another object type, e.g. a pump is a component of a pump station. Other relationships may be more general associations, e.g. a CCTV survey being associated with a pipe.

Relationship purpose must be specified at relationship creation time. See User Defined Relationship Dialog for more details.

The Object Browser Window can be used to show and manage object relationships. On this window, related objects are grouped by relationship purpose.

Relationship purpose	Description
Component	One object type is a component of the other. Component relationships usually exist between assets and are indicative of the fact that one asset may encompass one of more other assets. A typical example of Component relationship is pumping stations and pumps (A pumping station may contain several pumps).
Association	There is a general association between the objects. This is typically the relationship that exists between assets and surveys, repairs and incidents. A pipe may have an associated CCTV survey, and this relationship is referred to as an Association or Associated relationship.
Connection	This type of relationship defines a connection between objects. For example, a pipe is connected to a node.
Empty	Empty relationships are relationships that do not currently contain any object.  For example it is possible that a particular pipe does not have any associated CCTV surveys. In that case the relationship between this pipe and the CCTV survey object type is called Empty. Empty relationships may be displayed in the Object Browser Window.

For a relationship to work, it is necessary for an object type to store the information necessary to identify an object of the other type. The source and target terminology has been introduced to help understand how this works. The source object type has additional fields specified to allow objects of the target object type to be identified. Some examples are shown below:

Relationship Description	Source Object Type	Target Object Type
Pipe - CCTV Survey	CCTV Survey	Pipe
Pump Station - Pump	Pump	Pump Station
CCTV Survey - Repair	Pipe Repair	CCTV Survey

Relationship description naming convention is target - source. For a CCTV survey associated with a pipe, the relationship description will be pipe - CCTV survey.

It is possible for many source objects to refer to the same target object, e.g. many pumps can be in the same pump station. It is important to get this the correct way round when defining relationships.

Relationship type	Number of source fields	Source field name (defaults)	Source fields description	Definition
Simple	1	target_id	Target Id	One source object type to one target object type
Asset	2	target_asset_type target_id	Target Asset Type Target Id	One source object type to many target object types, usually asset types
All Node	1	node_id	Target Node Id	One source object to all nodes
All Link	1	link_id	Target Link Id	One source object to all links
Collection Pipe	3	target_us_node_id target_ds_node_id target_link_suffix	Target US/DS Node & Link Suffix	One object type to collection pipe objects

The source field names have default values as shown in the table above, but the user may choose to use other field names. This will be essential in the case where an object type is the source of more than one relationship (see below).

A relationship allows one source object to be related to one target object. In some cases, a source object may be related to more than one target object.

One example of this is a pipe repair. A pipe repair is related to the pipe to be repaired and the work package under which the work is carried out. This means that there are two relationships with pipe repair as the source object type. This is shown below:

Source Object	Relationship	Target Object
Pipe repair	Work package relationship	Work package
Pipe repair	Repaired pipe relationship	Pipe

Another example of this is the relationship between a Collection Network property object and its pipes. In this case the property has two relationships: one specifying the property’s sanitary pipe and one specifying the storm pipe. In this case, there are two separate relationships between the property object type and pipe object type.

Source Object	Relationship	Target Object
Property	Sanitary Pipe Relationship	Sanitary Pipe
Property	Storm Pipe Relationship	Storm Pipe

A source object type can have as many relationships as desired, but each relationship will have just a single target object.

To be able to use SQL to query relationships, it is necessary to define an SQL name for the relationship. The InfoAsset Manager SQL language already has many built-in relationship names.

For example to refer to the manhole properties when querying the Manhole repair table the manhole prefix is used to identify the joined object:

SELECT FROM [Manhole Repair] WHERE manhole.cover_dim > 500

Conversely, to interrogate the manhole repairs associated with a manhole the manhole_repairs prefix is used to find the many repairs:

SELECT id, COUNT(manhole_repairs.*) FROM Manhole

When defining a relationship, the SQL prefixes to be associated with the relationship should also be specified. This is done in the User Defined Relationship Dialog. For each relationship, there is a joined prefix (source to target relationship) and the one-to-many prefix (target to source relationship). See User Defined Relationship Dialog for more details.