what is difference between primary key and unique key
?

Answers were Sorted based on User's Feedback



what is difference between primary key and unique key ?..

Answer / chandonline

Basic difference between primary key and unique is that primary key is used to define a table in other tables for preventing data from anomalies,and unique key is used in a table to apply unifications among different values or columns of a tables and only in that table obviously.Their is no usage of unique key outward a table but primary key is often used to make relations between other tables.

Is This Answer Correct ?    3 Yes 0 No

what is difference between primary key and unique key ?..

Answer / ashish tyagi

The basic difference between primary key and unique key is that unique key allows null value but primary key did not allow null value.

Is This Answer Correct ?    2 Yes 0 No

Post New Answer

More DB Development Interview Questions

Explain the process of the user request and data generating?

0 Answers  


Explain about the database management systems.

0 Answers  


State the acid rules?

0 Answers  


Explain the rollup operator?

0 Answers  


Explain what a database is?

0 Answers  






Explain the general syntax for a SELECT statements covering all the options.

3 Answers  


What is bit datatype and what's the information that can be stored inside a bit column?

2 Answers  


What are the three basic rules which are to be followed for the relational model of the database?

0 Answers  


agregator gives one to many records or many to one record

1 Answers   IBM,


The count() function always returns a int value type what should you do if you need to count rows from a query which you know will return a value that is too large for an int value type?

0 Answers  


1. Using the XML Document below, with the URI “recipe.xml” define the following queries in XQuery: a.) Give the names of all breakfast in the menu. b.) Select breakfasts that have price lower than $7.00? <?xml version="1.0"?> <breakfast_menu> <food> <name>Belgian Waffles</name> <price>$5.95</price> <description> two of our famous Belgian Waffles with plenty of real maple syrup </description> <calories>650</calories> </food> <food> <name>Strawberry Belgian Waffles</name> <price>$7.95</price> <description> light Belgian waffles covered with strawberries and whipped cream </description> <calories>900</calories> </food> <food> <name>Berry-Berry Belgian Waffles</name> <price>$8.95</price> <description> light Belgian waffles covered with an assortment of fresh berries and whipped cream </description> <calories>900</calories> </food> <food> <name>French Toast</name> <price>$4.50</price> <description> thick slices made from our homemade sourdough bread </description> <calories>600</calories> </food> <food> <name>Homestyle Breakfast</name> <price>$6.95</price> <description> two eggs, bacon or sausage, toast, and our ever-popular hash browns </description> <calories>950</calories> </food> </breakfast_menu>

0 Answers  


Can an extended stored procedure be called from inside a user-defined function?

0 Answers  


Categories