Primary Key and Foreign Key
It can also be defined to reference the columns of a UNIQUE constraint in another table. The primary key is added successfully. Difference Between Primary Key And Foreign Key Online Tutorials Primary Tutorial In this tutorial you will learn what is a key in DBMS different types of keys and how these keys are defined and used during the database design stage. . Empid Empname Empid EmpPassport Empname EmpLicence Empname Any set of column which contains EmpLicence or EmpPassport or Empid is a super key of the table. Now lets learn about the foreign keys a well. Starting in Microsoft Dynamics AX 2012 the primary key for every new table is always enforced by an index that has exactly one field. A FOREIGN KEY constraint does not have to be linked only to a PRIMARY KEY constraint in another table. A foreign key enables you to link two or more tables together. Foreign key can accept multiple null value. In this ar...