ALLInterview.com :: Home Page            
 Advertise your Business Here     
Browse  |   Placement Papers  |   Company  |   Code Snippets  |   Certifications  |   Visa Questions
Post Question  |   Post Answer  |   My Panel  |   Search  |   Articles  |   Topics  |   ERRORS new
   Refer this Site  Refer This Site to Your Friends  Site Map  Bookmark this Site  Set it as your HomePage  Contact Us     Login  |  Sign Up                      
Google
   
 
Categories >> Software >> Databases >> SQL PLSQL
 
 


 

 
 Oracle interview questions  Oracle Interview Questions (2036)
 SQL Server interview questions  SQL Server Interview Questions (1076)
 MS Access interview questions  MS Access Interview Questions (24)
 MySQL interview questions  MySQL Interview Questions (194)
 Postgre interview questions  Postgre Interview Questions (6)
 Sybase interview questions  Sybase Interview Questions (22)
 DB Architecture interview questions  DB Architecture Interview Questions (5)
 DB Administration interview questions  DB Administration Interview Questions (213)
 DB Development interview questions  DB Development Interview Questions (53)
 SQL PLSQL interview questions  SQL PLSQL Interview Questions (773)
 Databases AllOther interview questions  Databases AllOther Interview Questions (106)
Question
what is the difference between trigger and constraint?
 Question Submitted By :: SQL-PLSQL
I also faced this Question!!     Answer Posted By  
 
Answer
# 1
Constraints implements specific conduct or rules on table column like it determines whether field data should be unique,not null ..
But triiger implements rules on systems or application event.
whenever dml occurs that implemented rules been fired.
 
Is This Answer Correct ?    3 Yes 0 No
Kumar Jabu
 
Answer
# 2
Triggers not apply for existing rows but constraints can
apply for existing rows.
 
Is This Answer Correct ?    1 Yes 0 No
Naga Sindhuri
 
 
 

 
 
 
Other SQL PLSQL Interview Questions
 
  Question Asked @ Answers
 
how can we write a column values horizontal by using sql stmt; ex: select name from table_name;(actual output) a b c d require output is a b c d Honeywell 3
what are the advantages of primary key over unique+notnull Oracle 7
What are different types of joins ? BirlaSoft 5
What are the default Oracle triggers?? CGI 2
How packaged procedures and functions are called from the following?   2
What is materialised View? IBM 1
How to trace the errors in pl/sql block code? TCS 4
How do you get all records from 2 tables. Which join do you use? Microsoft 8
..........refers to the disk mirroring iFlex 2
Its possible to add more than one primary key for the table   3
i declare 4 procedure in package specification but in package body i write only 3 procedure. is it complie??//w Scope-International 4
how to check the 3rd max salary from an employee table? One of the queries used is as follows: select sal from emp a where 3=(select count(distinct(sal)) from emp b where a.sal<=b.sal). Here in the sub query "select count(distinct(sal)) from emp b where a.sal<=b.sal" or "select count(distinct(sal)) from emp b where a.sal=b.sal" should reveal the same number of rows is in't it? Can any one here please explain me how is this query working perfectly. However, there is another query to get the 3rd highest of salaries of employees that logic I can understand. Pls find the query below. "select min(salary) from emp where salary in(select distinct top 3 salary from emp order by salary desc)" Please explain me how "select sal from emp a where 3=(select count(distinct(sal)) from emp b where a.sal<=b.sal)" works source:http://www.allinterview.com/showanswers/33264.html. Thanks in advance Regards, Karthik.   4
 
For more SQL PLSQL Interview Questions Click Here 
 
 
 
 
 


   
Copyright Policy  |  Terms of Service  |  Articles  |  Site Map  |  RSS Site Map  |  Contact Us
   
Copyright 2013  ALLInterview.com.  All Rights Reserved.

ALLInterview.com   ::  KalAajKal.com