In a one-to-many relationship, the multiple side consists of a collection of entities. An identification variable can represent a member of this collection. To access a collection member, the path expression in the variable’s declaration navigates through the relationships in the abstract schema. (For more information on path expressions, see the following section.) Because a path expression can be based on another path expression, the navigation can traverse several relationships. See Traversing Multiple Relationships.
A collection member declaration must include the IN operator, but it can omit the optional AS operator.
In the following example, the entity represented by the abstract schema named Player has a relationship field called teams. The identification variable called t represents a single member of the teams collection.
FROM Player p, IN (p.tea ms) t