Some interview questions

Question

Hello All Please anybody answer me the following questions which was asked to recently What is normalization explain in brief?what is firstsecondthirdfourthfifth and sixth normal form explain with example? what is the difference between foreign key and unique key? what is the difference between primary key and unique key? Thanks & Regards Prashant S. More

Rahul Saxena · Answer

Primary Key - Is the key that Uniquely indentifies a row and the field/column must contain value. P rimary key is not NULL. Unquie Key - Is the key that Uniquely indentifies a row and the field/column and may or many not contain value Foreign Key - Is the Key that referes to Primary or Unique Key of the same or different Table. Foreign key is NULL.