SQL allows a foreign-key dependency to refer to the same relation, as in the following example: create table manager (employee ID char(20), manager ID char(20), primary key employee ID, foreign key...

SQL allows a foreign-key dependency to refer to the same relation, as in the
following example:
create table manager
(employee ID char(20),
manager ID char(20),
primary key employee ID,
foreign key (manager ID) references manager(employee ID)
on delete cascade )
Here, employee ID is a key to the table manager, meaning that each employee
has at most one manager. The foreign-key clause requires that every manager
also be an employee. Explain exactly what happens when a tuple in the relation
manager is deleted.

Jun 09, 2022

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SQL allows a foreign-key dependency to refer to the same relation, as in the following example: create table manager (employee ID char(20), manager ID char(20), primary key employee ID, foreign key...

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