TableCollection.CreateRelation method creates a relationship between two tables when you want to associate rows of one table with rows of another table. It takes the following arguments.
- primaryIndex: An IIndex that specifies the primary key.
- foreignIndex: An IIndex that specifies the foreign key.
- convertForeignToPrimary: A function to convert a foreign key to the corresponding primary key.
- convertPrimaryToForeign: A function to convert a primary key to the corresponding foreign key.
- relationOptions: An RelationOptions that specifies options of a relation.
To create an index, NMemory provides Table.CreateIndex method which creates a new index in a table and it takes two arguments.
- indexFactory: The index factory.
- keySelector: The expression representing the definition of the index key.
The columns you choose for the foreign key must have the same data type of the primary columns they correspond to.