Two relational primary key associations and foreign key associations for one-to-one databases

Association mappings: one-to-one

One to one relationship is the relationship between the team and the team's address, a team only has an address, and an address area has only one team.

There are two kinds of data table-to-one relationships: a foreign key association and a primary key association. This is illustrated below:

One-to-one foreign key association:

Two-to-one primary key association: requires that the primary key of both tables be exactly the same, and that the correlation is established by the primary key of two tables

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