Hello All,
Please anybody answer me the following questions which was asked to recently
What is normalization explain in brief?what is first,second,third,fourth,fifth 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 Kumar SaxenaPosted Nov 6, 2008, 4:37 AM
Primary Key - Is the key that Uniquely indentifies a row and the field/column must contain value. Primary 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.