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What is the relationship between foreign key and candidate key?
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What are the differences between super key primary key candidate key and foreign key?
Super key: A set of attributes that uniquely identifies a tuple in a table. Primary key: A specific super key chosen to uniquely identify each tuple in a table and must be unique and not null. Candidate key: Any super key that could be chosen as the primary key. Foreign key: A field in a table that is a primary key in another table, used to establish a relationship between the two tables.
Why is a field with an autonumber data type not a good candidate for the foreign key field for a one to many relationship?
The foreign key has to match the information from the corresponding record in the other table.
What key defines a relationship between two tables 1 Primary key 2 Secondary key 3 Foreign key?
Foreign key is used to define a relationship between two tables by referencing the primary key of another table. It ensures data integrity and enforces referential integrity between the related tables.
When a relationship exists between two tables in a database for Microsoft acess what name is given to the matching field in the related table?
The field in a related table that matches a field in another table is called a foreign key. This foreign key establishes the relationship between the two tables in a database.
What happen when you delete foreign key?
You will lose the connection between the tables and break the relationship.
What is a foreign key in Microsoft Access?
It is a field in one table that is a primary key in another table. It is used to create a relationship between two tables, normally a one to many relationship. The one side is where it is the primary key and where it is the foreign key, that is the many tables.
Why do you designate one of the candidate key of relation to be the primary key?
We designate one of the candidate key of a relation to be a primary key because that primary key is use for any foreign key references.
What is the difference between a primary key and a foreign key?
A primary key uniquely identifies each record in a table and ensures data integrity. A foreign key establishes a relationship between two tables, referencing the primary key of another table to enforce referential integrity.
What role does a foreign key play in the establishment of a relationship between two entities or tables?
A foreign key is a column or a set of columns in one table that references the primary key in another table, creating a relationship between the two. This relationship ensures data integrity by enforcing referential integrity constraints, allowing for the proper establishment of connections between related data in a database. It helps maintain data consistency by preventing actions that would create orphaned records or violate the defined relationship between the tables.
What is the condition for a key to be a foreign key?
A key is considered a foreign key if it references the primary key of another table to establish a relationship between the two tables. It enforces referential integrity, ensuring that data in the foreign key column corresponds to data in the primary key column.
Types of keys in database management system?
super key foreign key candidate key surrogate key unique key alternate key composite key compound key
Is a foreign key field always on the one side of a one-to-many relationship between two tables?
No. The foreign key is always on the many side. A foreign key is a field that is a primary key in another table, not in the table it is in. It can therefore be repeated in the table it is, so it can act as the many side. In its own table, it is the primary key, and only appears once.
