association "association-name"
    principal "principal-entityset-name" ("column-name"[ , ... ]) multiplicity "[ 1 | 0...1 | 1..* | * ]"
    dependent "dependent-entityset-name" ("column-name"[ , ... ]) multiplicity "[ 1 | 0...1 | 1..* | * ]"
    over "owner"."object-name" principal ("column-name"[ , ... ]) dependent ("column-name"[ , ... ])

Associations are created with the foreign keys defined in the database if they are not specified in the model.

In an association that does not have an association table, the number of join properties for the principal end must match the number of join properties for the dependent end.

In an association that has an association table, the number of join properties for the principal end must match the number of association table principal end join properties, and the number of join properties of the dependent end must match the number of association table dependent end properties.

When defining an association between two tables, the dependent table should reference the principal table.

The ordering of join properties for principal and dependent ends is relevant. The first column of the principal end is matched with the first column of the dependent end, and so on. The matching columns must also be the same.

The following is an example of a simple association:

service namespace "OSDLExample" {

    entity "dba"."T1" as "T1" navigates( "T1_T2_REL" as "T2" );
    entity "dba"."T2" as "T2" navigates( "T1_T2_REL" as "T1" );

    association "T1_T2_REL"
        principal "T2" ("pk1") multiplicity "*"
        dependent "T1" ("pk1") multiplicity "*"
        over "dba"."AssocTable" principal ("t2_pk1") dependent ("t1_pk1");
}