One (optional) to One (mandatory) [recursive]
Diagram | ![]() |
---|---|
How to read | One employee may manage one other employee, but each employee is managed by exactly one employee. |
Relevant relations | None. |
The table structure is as follows:
employee(__id__, name, mgr_id*, <e_other>)
The SQL create statement is as follows:
create table employee
(id type primary key,
name type,
mgr_id type not null,
<e_other>,
foreign key (mgr_id) references employee);
Since this relationship is optional in one direction, this is the only way this relationship should be represented in the database.
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page revision: 1, last edited: 21 Aug 2008 00:30