One (optional) to Many [recursive]
|How to read||One employee may manage many employees. Each employee may be managed by a manager.|
|Relevant relations||The many side of this relation can be either optional or mandatory.|
The table structures are as follows:
employee(__id__, name, <e_other>) manage(__emp_id__*, mgr_id*)
The SQL create statement is as follows:
create table employee (id type primary key, name type, <e_other>); create table manage (emp_id type primary key, mgr_id type not null, foreign key (mgr_id) references employee, foreign key (emp_id) references employee);
The reader should note that mgr_id cannot be the primary key of manage because many employees can have the same manager.
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page revision: 2, last edited: 21 Aug 2008 00:35