Relation Text | Relation Image | Rules |
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1:1 |
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Combine the tables or take the primary key from one into the other. |
1:1 with Optionality on one end |
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Take the primary key from the non-optional end and put it as a foreign key in the optional end. |
1:1 with Optionality on both ends |
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Create a new link table using the primary key from one table as a foreign primary key in the new table. The other table's primary key is also put in the new table as a foreign key. |
1:M 1:M with Optionality on the many end |
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Primary key from the 1 side of the relationship is put into the many table as a foreign key. |
1:M with Optionality on the one end 1:M with Optionality on both ends |
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Create a new link table using the primary key from the one end as a foreign primary key in the new table. The primary key from the many end is also put in the new table as a foreign key. |
M:N M:N with Optionality on one end M:N with Optionality on both ends |
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Create a new link table using the primary keys of each table as a compound primary key in the new table |