Sqlserver Interview questions

Total available count: 45
Subject - Databases
Subsubject - Sqlserver

What is Unique key constraint?

A Unique key constraint enforces the uniqueness of the values in a set of columns, so no duplicate values are entered. The unique key constraints are used to enforce entity integrity as the primary key constraints.

A programmer can have many Unique key constraints per table, but only one Primary key constraint per table.

    empid int NOT NULL UNIQUE,
    empname varchar(255) NOT NULL,
    age varchar(255),
    address varchar(255),
    city varchar(255)


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What is a Primary key?