![]() For an example, see Add multiple foreign key constraints to a single column. A single column can have multiple foreign key constraints.A foreign key column cannot be a virtual computed column, but it can be a stored computed column.Foreign key columns must use their referenced column's type.(For diagrammatic modeling) Select this checkbox to automatically display this screen whenever an Association is created between two Tables.Ĭlick on this button to delete the currently selected existing (saved) Foreign Key.Ī prompt is displayed to confirm the deletion (and the deletion of the Foreign Key Index, if one exists) - click on the Yes button.ĭeleting a Foreign Key leaves an Association connector in place, which you can either edit or delete (right-click and select 'Delete association: to ').Ĭlick on this button to save the Foreign Key.To read more about how foreign keys work, see our What is a Foreign Key? (With SQL Examples) blog post. The name of the Foreign Key Index is controlled by the Foreign Key Index template, and the generated name is shown in the 'Name' field underneath the 'Create?' field.Īutomatically show this screen when tables are joined If you want to create a Foreign Key Index at the same time as the Foreign Key, set this property to True. Select the action that should be taken on the data in the child Table when data in the parent is updated, so as to maintain referential integrity.Ĭlick on the drop-down arrow and select the cardinality of the parent Table in the Foreign Key.Ĭlick on the drop-down arrow and select the cardinality of the child Table in the Foreign Key. Select the action that should be taken on the data in the child Table when data in the parent is deleted, so as to maintain referential integrity. To change the name to something other than the default, simply overtype the value. This field defines the name of the Foreign Key constraint, and defaults to a name constructed by the Foreign Key Name Template. Select an existing column (click on the drop-down arrow and select the name from the list).However, if you want to force the pairing to an existing child Table column or a new column with a different name, click on the column name field and either: If the child Table does not have a column of the same name, a new column of that name will be added to the list, flagged with (*) to indicate that a new column will be created in the Table. On the child side the system will automatically attempt to match each parent column to one of the same name in the child Table. ![]() When a constraint is selected (in the 'Join on constraint' field) the parent side is refreshed to display all columns assigned to the selected constraint. This list is divided into two: the columns involved in the selected constraint are listed on the left, and the child columns that are going to be paired to the parent columns are listed on the right. When you select the constraint, its columns are automatically listed in the 'Involved Columns' panel, under the 'Parent: ' column. The first constraint in the list is selected by default if this is not the constraint you want, select the correct constraint from the combo box. (These constraints can be Primary Keys, Unique Constraints or Unique Indexes.) This combo box lists all defined constraints in the parent Table that could be used as the basis of a Foreign Key. The parent Table must have a Primary Key, unique constraint or unique index definedĬreate a Foreign Key - using the Database Builder. ![]() ![]()
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