difference between primary key and unique key in sql with example
difference between primary key and foreign key in mysqldifference between primary key and foreign key with example
primary key and unique key example
difference between primary key and unique key with example
difference between primary key and unique key in oracle
difference between primary key and unique key and foreign key
difference between primary key and unique key and foreign key and composite key

Keys are crucial to the table structure in a relational database. this unique index is designated as the primary index when DB2 is operating in new-function A foreign key is a key that is specified in the definition of a referential constraint in a 4 Jul 2007 Back to the Basics: Difference between Primary Key and Unique Index different RDBMS treat this differently –> while SQL Server and DB2 do 23 Nov 2018 The difference between Primary key, Unique key and Foreign Key is the most common interview question for .NET as well as SQL developers. Learn why the primary key and foreign key are both important to maintaining your database's integrity. Between them the PK and FK establish relationships. 12 Aug 2017 SQL Queries Examples for Composite Primary Key,Foreign Key and Unique key is same as primary with difference being the existence of 31 Jan 2019 Online Tutorials & Training Materials | STechies.com Before we delve into the difference between unique key and primary key, it is important to In SQL Server, the following characteristics are depicted by unique keys:. 22 Sep 2014 Behavior: Primary Key is used to identify a row (record) in a table, whereas Unique-key is to prevent duplicate values in a column (with the exception of a null entry). 2. Indexing: By default SQL-engine creates Clustered Index on primary-key if not exists and Non-Clustered Index on Unique-key. One difference is that a unique key constraint can be created over columns with null values, while a primary key constraint does not allow null values. The other difference is that there can only be one primary key constraint defined on a table, but there can be multiple unique key constraints defined on a table.Whats the difference between a primary and unique key? When should you use one over the other to define your SQL Server Table? 20 Oct 2012