What is a primary key key?

Question

A primary key is the column or columns that contain values that uniquely identify each row in a table. A database table must have a primary key for Optim to insert, update, restore, or delete data from a database table.

What is a primary key give example?

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

Why is a primary key?

The main purpose of primary key is to identify the uniqueness of a row, where as unique key is to prevent the duplicates, following are the main difference between primary key and unique key. Primary Key : There can only be one primary key for a table. The primary key consists of one or more columns.

What is primary key and secondary key?

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.

What is a primary key class 8?

Answer: Primary key is a field that uniquely identifies each record in a table. For example, in a school database, the Roll Number of each student uniquely identifies each student. A Primary key does not allow Null Values and must always have a unique value.

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