Erotischer chat one to one
Also note that you can put the foreign key on the parent table, to the child, instead of the other way around.In this way, you can prevent one-to-many if you want to do that.But the database does not know whether this is a one-to-one or one-to-many relationship right?
Your sentence "And in a one-to-many relationship the table contains many foreign keys." The table of the 'many' side still contains one column that is a foreign key, its just that more than one row can have the same foreign key value (many rows point to one parent).And all the time, you want to "save" rows/columns in table not duplicating them you will use one-to-many relation with another table.Or many-to-many :) Let's assume you have a table with two attributes A and B.I do not completely grasp the idea of the relationships, even though I have read many tutorials about this. to the database, they are constructs we have invented to better understand how to design the tables.The big difference in terms of table structure between one-to-one and one-to-many is that in one-to-one it is possible (but not necessary) to have a bidirectional relationship, meaning table A can have a foreign key into table B, and table B can have a foreign key into the associated record in table A.