Can Primary Key Values Be Changed? The PRIMARY KEY constraint specifies that the constrained columns’ values must uniquely identify each row. … You can change the primary key of an existing table with an ALTER TABLE … ALTER PRIMARY KEY statement, or by using DROP CONSTRAINT and then ADD CONSTRAINT in the same transaction. How
Which Table Is An Intersection Table? An intersection table is a table that defines a many-to-many relationship. It provides an intersection between two business components. A many-to-many relationship is one in which there is a one-to-many relationship from either direction. For example, there is a many-to-many relationship between Accounts and Contacts. What is an intersection
Is Foreign Key Unique? S.NO. PRIMARY KEY FOREIGN KEY 4 It is a combination of UNIQUE and Not Null constraints. It can contain duplicate values and a table in a relational database. Can foreign key be not unique? No, foreign keys do not have to be unique. Indeed, a lack of uniqueness is requisite for