What are primary keys in DBMS?

What is primary key in DBMS and example?

A primary key is a column -- or a group of columns -- in a table that uniquely identifies the rows of data in that table. For example, in the table below, CustomerNo, which displays the ID number assigned to different customers, is the primary key. CUSTOMERS. CustomerNo.

What is primary key and explain its types?

Primary Key The primary key refers to a column or a set of columns of a table that helps us identify all the records uniquely present in that table. A table can consist of just one primary key. Also, this primary key cannot consist of the same values reappearing/repeating for any of its rows.

What are the 5 types of primary key?

Primary Key.Candidate Key.Alternate Key.Super Key.Composite Key.Foreign Key.Unique Key.

What are primary and secondary keys?

A primary key is the field in a database that is the primary key used to uniquely identify a record in a database. A secondary key is an additional key, or alternate key, which can be use in addition to the primary key to locate specific data.