Crow's Foot notation and identifying -vs- non-identifying relationships
Is it possible to distinguish between identifying and non-identifying relationships using the Crow's Foot notation?
Case in point: In table Book, part of the book's Primary Key is a FK to the Author table. In other words I embed the author's identifier in the book's identifier. Also, a book has a FK to a Book_Type (containing values like "hardcover", "papercover") (this is just an example, I understand that I would probably need a "book edition" table for that).
The thing is that this latter FK relationship isn't nearly really as important as the former one (the FK to Book_Type is not part of Book's Primary Key), yet my understanding is that in the Crow's Foot diagram shown below, both these relationships are rendered identically:
Have I misunderstood something or is there a way to signify the identifying versus non-identifying relationship distinction using the Crow's Foot notation?
foreign-key primary-key database-diagrams
asked May 25 '14 at 16:08
Marcus Junius BrutusMarcus Junius Brutus
1,01441430
bumped to the homepage by Community♦ 28 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
add a comment |
Is it possible to distinguish between identifying and non-identifying relationships using the Crow's Foot notation?
Case in point: In table Book, part of the book's Primary Key is a FK to the Author table. In other words I embed the author's identifier in the book's identifier. Also, a book has a FK to a Book_Type (containing values like "hardcover", "papercover") (this is just an example, I understand that I would probably need a "book edition" table for that).
The thing is that this latter FK relationship isn't nearly really as important as the former one (the FK to Book_Type is not part of Book's Primary Key), yet my understanding is that in the Crow's Foot diagram shown below, both these relationships are rendered identically:
Have I misunderstood something or is there a way to signify the identifying versus non-identifying relationship distinction using the Crow's Foot notation?
foreign-key primary-key database-diagrams
asked May 25 '14 at 16:08
Marcus Junius BrutusMarcus Junius Brutus
1,01441430
bumped to the homepage by Community♦ 28 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
An Entity-Relationship Diagram (ERD), of which "crows-feet" is just one type of notation, describes only the relationship between entities. The Primary Key (PK) of an entity can normally be inferred from that but there are things you can do in creating a PK that are not clearly reflected in an ERD. By making the Book PK consist of the Author PK plus something else that is not a foreign-key (FK) (you didn't what) you are describing one of those. It would be much more flexible to just use auto-generated sequence numbers for the FKs of all tables.
– DocSalvager
May 28 '14 at 8:22
add a comment |
Is it possible to distinguish between identifying and non-identifying relationships using the Crow's Foot notation?
Case in point: In table Book, part of the book's Primary Key is a FK to the Author table. In other words I embed the author's identifier in the book's identifier. Also, a book has a FK to a Book_Type (containing values like "hardcover", "papercover") (this is just an example, I understand that I would probably need a "book edition" table for that).
The thing is that this latter FK relationship isn't nearly really as important as the former one (the FK to Book_Type is not part of Book's Primary Key), yet my understanding is that in the Crow's Foot diagram shown below, both these relationships are rendered identically:
Have I misunderstood something or is there a way to signify the identifying versus non-identifying relationship distinction using the Crow's Foot notation?
foreign-key primary-key database-diagrams
asked May 25 '14 at 16:08
Marcus Junius BrutusMarcus Junius Brutus
1,01441430
Is it possible to distinguish between identifying and non-identifying relationships using the Crow's Foot notation?
Case in point: In table Book, part of the book's Primary Key is a FK to the Author table. In other words I embed the author's identifier in the book's identifier. Also, a book has a FK to a Book_Type (containing values like "hardcover", "papercover") (this is just an example, I understand that I would probably need a "book edition" table for that).
The thing is that this latter FK relationship isn't nearly really as important as the former one (the FK to Book_Type is not part of Book's Primary Key), yet my understanding is that in the Crow's Foot diagram shown below, both these relationships are rendered identically:
Have I misunderstood something or is there a way to signify the identifying versus non-identifying relationship distinction using the Crow's Foot notation?
foreign-key primary-key database-diagrams
foreign-key primary-key database-diagrams
asked May 25 '14 at 16:08
Marcus Junius BrutusMarcus Junius Brutus
1,01441430
asked May 25 '14 at 16:08
Marcus Junius BrutusMarcus Junius Brutus
1,01441430
edited Mar 15 '17 at 15:20
Marcus Junius Brutus
asked May 25 '14 at 16:08
Marcus Junius BrutusMarcus Junius Brutus
1,01441430
asked May 25 '14 at 16:08
Marcus Junius BrutusMarcus Junius Brutus
1,01441430
asked May 25 '14 at 16:08
Marcus Junius BrutusMarcus Junius Brutus
1,01441430
1,01441430
bumped to the homepage by Community♦ 28 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
bumped to the homepage by Community♦ 28 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
An Entity-Relationship Diagram (ERD), of which "crows-feet" is just one type of notation, describes only the relationship between entities. The Primary Key (PK) of an entity can normally be inferred from that but there are things you can do in creating a PK that are not clearly reflected in an ERD. By making the Book PK consist of the Author PK plus something else that is not a foreign-key (FK) (you didn't what) you are describing one of those. It would be much more flexible to just use auto-generated sequence numbers for the FKs of all tables.
– DocSalvager
May 28 '14 at 8:22
add a comment |
An Entity-Relationship Diagram (ERD), of which "crows-feet" is just one type of notation, describes only the relationship between entities. The Primary Key (PK) of an entity can normally be inferred from that but there are things you can do in creating a PK that are not clearly reflected in an ERD. By making the Book PK consist of the Author PK plus something else that is not a foreign-key (FK) (you didn't what) you are describing one of those. It would be much more flexible to just use auto-generated sequence numbers for the FKs of all tables.
– DocSalvager
May 28 '14 at 8:22
An Entity-Relationship Diagram (ERD), of which "crows-feet" is just one type of notation, describes only the relationship between entities. The Primary Key (PK) of an entity can normally be inferred from that but there are things you can do in creating a PK that are not clearly reflected in an ERD. By making the Book PK consist of the Author PK plus something else that is not a foreign-key (FK) (you didn't what) you are describing one of those. It would be much more flexible to just use auto-generated sequence numbers for the FKs of all tables.
– DocSalvager
May 28 '14 at 8:22
An Entity-Relationship Diagram (ERD), of which "crows-feet" is just one type of notation, describes only the relationship between entities. The Primary Key (PK) of an entity can normally be inferred from that but there are things you can do in creating a PK that are not clearly reflected in an ERD. By making the Book PK consist of the Author PK plus something else that is not a foreign-key (FK) (you didn't what) you are describing one of those. It would be much more flexible to just use auto-generated sequence numbers for the FKs of all tables.
– DocSalvager
May 28 '14 at 8:22
add a comment |
2 Answers
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Different ERD notations offer different relationship decorations for identifying relationships. The most common that I've seen is the use of solid lines for identifying and dashed lines for non-identifying.
answered Nov 25 '18 at 8:32
Russell SearleRussell Searle
1
add a comment |
In your diagram, you are showing both entities as solid lines indicating identifying relationships. Non-identifying relationships are shown with dashed lines.
answered Mar 14 '17 at 14:30
Jeffreyb723Jeffreyb723
1
add a comment |
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2 Answers
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2 Answers
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Different ERD notations offer different relationship decorations for identifying relationships. The most common that I've seen is the use of solid lines for identifying and dashed lines for non-identifying.
answered Nov 25 '18 at 8:32
Russell SearleRussell Searle
1
add a comment |
Different ERD notations offer different relationship decorations for identifying relationships. The most common that I've seen is the use of solid lines for identifying and dashed lines for non-identifying.
answered Nov 25 '18 at 8:32
Russell SearleRussell Searle
1
add a comment |
Different ERD notations offer different relationship decorations for identifying relationships. The most common that I've seen is the use of solid lines for identifying and dashed lines for non-identifying.
answered Nov 25 '18 at 8:32
Russell SearleRussell Searle
1
Different ERD notations offer different relationship decorations for identifying relationships. The most common that I've seen is the use of solid lines for identifying and dashed lines for non-identifying.
answered Nov 25 '18 at 8:32
Russell SearleRussell Searle
1
answered Nov 25 '18 at 8:32
Russell SearleRussell Searle
1
answered Nov 25 '18 at 8:32
Russell SearleRussell Searle
1
answered Nov 25 '18 at 8:32
Russell SearleRussell Searle
1
1
add a comment |
add a comment |
In your diagram, you are showing both entities as solid lines indicating identifying relationships. Non-identifying relationships are shown with dashed lines.
answered Mar 14 '17 at 14:30
Jeffreyb723Jeffreyb723
1
add a comment |
In your diagram, you are showing both entities as solid lines indicating identifying relationships. Non-identifying relationships are shown with dashed lines.
answered Mar 14 '17 at 14:30
Jeffreyb723Jeffreyb723
1
add a comment |
In your diagram, you are showing both entities as solid lines indicating identifying relationships. Non-identifying relationships are shown with dashed lines.
answered Mar 14 '17 at 14:30
Jeffreyb723Jeffreyb723
1
In your diagram, you are showing both entities as solid lines indicating identifying relationships. Non-identifying relationships are shown with dashed lines.
answered Mar 14 '17 at 14:30
Jeffreyb723Jeffreyb723
1
answered Mar 14 '17 at 14:30
Jeffreyb723Jeffreyb723
1
answered Mar 14 '17 at 14:30
Jeffreyb723Jeffreyb723
1
answered Mar 14 '17 at 14:30
Jeffreyb723Jeffreyb723
1
1
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add a comment |
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An Entity-Relationship Diagram (ERD), of which "crows-feet" is just one type of notation, describes only the relationship between entities. The Primary Key (PK) of an entity can normally be inferred from that but there are things you can do in creating a PK that are not clearly reflected in an ERD. By making the Book PK consist of the Author PK plus something else that is not a foreign-key (FK) (you didn't what) you are describing one of those. It would be much more flexible to just use auto-generated sequence numbers for the FKs of all tables.
– DocSalvager
May 28 '14 at 8:22