Category Archives: SQL Primary Key Constraint

SQL Primary Key & Constraints

Difference between Primary key and Unique key

Posted on October 5, 2009 by vivekjohari

var gaJsHost = ((“https:” == document.location.protocol) ? “https://ssl.” : “http://www.”); document.write(unescape(“%3Cscript src=’” + gaJsHost + “google-analytics.com/ga.js’ type=’text/javascript’%3E%3C/script%3E”)); try { var pageTracker = _gat._getTracker(“UA-11608194-1”); pageTracker._trackPageview(); } catch(err) {} Both Primary key and Unique key enforce uniqueness of the column on which … Continue reading →

Posted in Imp SQL Difference, Interview Questions, SQL Primary Key Constraint, SQL Server | Tagged | 30 Comments

Sql server Constraints – Primary Key, Foreign Key, Unique Key, Not Null, Check Constraints

Posted on August 19, 2009 by vivekjohari

Introduction A constraint is a property that is assigned to a column or a group of columns to prevent incorrect or corrupt data from entering into the tables. These constraints ensure the accuracy and reliability of the data into the … Continue reading →

Posted in Most Imp SQL Concepts, SQL Primary Key Constraint, SQL Server | Tagged , , , | 31 Comments