Access Database Design and Programming, Second Edition

Creating a Relation

Relations are created in DAO using the CreateRelation method. The syntax is:

Set RelationVar = DatabaseVar.CreateRelation _
([RelName[, KeyTable[, ForeignTable[, Attributes]]]])

where:

• RelName is the name of the new relation.

• KeyTable is the name of the referenced table in the relation (containing the key).

• ForeignTable is the name of the referencing table in the relation (containing the foreign key).

• Attributes is a constant, whose values are shown in Table 15.2.

Table 15-2. Attributes for a Relation Object

Constant	Description
dbRelationUnique	Relationship is one-to-one
dbRelationDontEnforce	No referential integrity
dbRelationInherited	Relationship exists in a noncurrent database that contains the two attached tables
dbRelationUpdateCascade	Cascading updates enabled
dbRelationDeleteCascade	Cascading deletions enabled

Notes

• All of the properties of a Relation object become read-only after the object is appended to a Relations collection.

• Field objects for the referenced and referencing tables must be appended to the Fields collection prior to appending the Relation object to the Relations collection.

• Duplicate or invalid names will cause an error when the Append method is invoked.

• To remove a Relation object from a collection, use the Delete method for that collection.

Example 15.4 illustrates the use of Relation objects. In this example, we will create a new relation in the LIBRARY database. The first step is to create a new table, using Microsoft ...