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Foreign keys and updates

CASCADE deletion

delete from P where p_id = 3;

P

p_id	x
1	123
2	456
3	789
4	111

F

f_id	p_id	y
1001	1	999
1002	1	888
2001	2	777
3001	3	666
3002	3	555
3003	3	444

→

P

p_id	x
1	123
2	456
4	111

F

f_id	p_id	y
1001	1	999
1002	1	888
2001	2	777

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