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Can primary key and foreign key be same?
Yes, it is legal to have a primary key being a foreign key. This is a rare construct, but it applies for: a 1:1 relation. The two tables cannot be merged in one because of different permissions and privileges only apply at table level (as of 2017, such a database would be odd).
Is foreign key always a primary key?
Primary keys always need to be unique, foreign keys need to allow non-unique values if the table is a one-to-many relationship. It is perfectly fine to use a foreign key as the primary key if the table is connected by a one-to-one relationship, not a one-to-many relationship.
How to use an auto incremented primary key as a foreign key?
How to use an auto incremented primary key as a foreign key as well? I have 2 tables… As you can see the table parent has an auto-incremented primary key “id”, which is also being used as a foreign key for the child table.
How to remember the name of the foreign key column?
It’s much easier to remember the name of the foreign key column when it’s “id” than when it’s “LastName” in this table, “RegistrationNo” in that table… 100 % of the world has lost data at some point and when this happens it can essentially isolate the FK based table.
How to use auto incremented primary key in MySQL?
If I start by creating a record in the child table, set it’s parent_id to 1, then reset the auto-increment counter of the parent table (so that the next insert will have id = 1), it works! But that’s not a solution. I don’t see the utility of the insert blocking if there is no related row in the child table…
Where is the foreign key in SQL Server?
I have the following two connected tables as shown below in the Microsoft SQL Server. When inserting data from visual studio, the foreign key in the Reservations table ( Customer_ID) should be auto incremented and have the same value as the Primary key of the parent table Customer_Info ( Customer_ID ).