Relation Notations

Foreign key relations are displayed as lines connecting tables. Appearance of the relation depends on the selected notation. dbForge Studio supports IE and IDEF1X notations for the diagrams.

IDEF1X Notation

IDEF1X (Integration Definition for Information Modeling) is a modeling language for developing a logical model of data.

Identifying relations are displayed as continuous lines with black circle on the child end. (Identifying relation means when all foreign key columns are included to the primary key of the child table). See an example below.

Relations

Non-identifying relations are displayed as dotted lines with black circle on the child end. If this relation is an Optional Non-Identifying Relationship (child foreign key columns are nullable), white diamond is displayed on the parent end of the relation. See examples below.

Relations

Relations

letter Z at the child end of the relationship appears if there can be only zero or one child record. It depends on whether the foreign key columns in the child table are unique (belong to the primary key or unique index). Thus, identifying relations are always displayed with letter Z. Non-identifying relations can be displayed both with or without Z letter.

IE Notation

IE Notation is used by default. Relations are displayed as continuous lines. Ends of the lines depend on relation cardinality. Relation cardinality is determined automatically from the foreign key constraint, it cannot be specified by user (except for editing child table constraints).

In Microsoft SQL Server one record of the child table corresponds to 0..1 (zero or one) or 1 (exactly one) record from the parent table. It depends on the presence of the NOT NULL constraints on the foreign key columns in the child table.

One record of the parent table corresponds to 0..1 (zero or one) or 0..N (zero, one, or more) records from the child table. It depends on whether the foreign key columns in the child table are unique (belong to the primary key or unique index).

Parent record Child record Example
1 (exactly one) 0..N (zero, one, or more Relations
1 (exactly one) 0..1 (zero or one) Relations
0..1 (zero or one) 0..N (zero, one, or more Relations
0..1 (zero or one) 0..1 (zero or one) Relations