The basic form for a participation constraint is *min*:*max*, where
*min* is a nonnegative integer,
and *max* is either a nonnegative integer or a star (*).
The star designates an arbitrary nonnegative number greater than *min*.
The most common participation constraints are 0:1, 1:1, 0:*, and 1:*.

In an ORM diagram, we place a participation constraint near the connection of the object class and relationship set to which it applies.

For instance:

**Figure 1. Sample participation constraints**

This example means that each object *person* in object class **Person** has one and only
one object *height* in object class **Height**, while each object *height* in object class
**Height** corresponds to zero or more object *person* in object class **Person**.

Instead of using nonnegative integers, we may also use variables.

**Figure 2. Variables in participation constraints**

**Figure 3. Shorthand participation constraints**

Here is a short quiz so you can test your understanding of participation constraints.

Go to the OSA Tutorial ORM

Go to Constraints Co-occurence Constraints

Last updated 3 Nov 1994. by Mingkang Xu (xmk@osm7.cs.byu.edu), Lei Cao(caol@bert.cs.byu.edu)