# Join Columns tab

This table lists the fields available on the Join Table tab in Properties view for Many-to-one mapping and One-to-one mapping mapping types.

Property | Description | Default
--- | --- | ---
Join Column | Specify a mapped column for joining an entity association. This field corresponds to the `@JoinColum` attribute. Select Override Default, then Add, Edit, or Remove the join columns. | By default, the mapping is assumed to have a single join.

Mapping an entity

Edit Join Columns Dialog