basic concepts of OOPS

The following are the basic concepts of OOPS.

1)Objects
2)Classes
3)Data Abstraction
4)Data Encapsulation
5)Inheritance

6)Polymorphism
7)Message Passing
8)Reusability
9)Dynamic Binding
10)Methods

What is difference between Trigger and a Stored Pr.

TRIGGER

1- when you create a trigger you have to identify event and action of your trigger but when you create s.p you don't identify event and action

2-trigger is run automatically if the event is occured but s.p don't run automatically but you have to run it manually

3- within a trigger you can call specific s.p but within a s.p you cann;t call atrigger

Difference between Truncate and Delete ?
Truncate is a DDL command and hence cant be rolled back
Truncate can not fire a trigger.
Truncate is unconditional.
Truncate removes all records but using this we cannot
remove a particular record.
where as delete is DML command and thus can be rolled back.
Delete can fire a trigger.
We can specify a condition while using deletecommand.

Difference between Dataset and DataReader : Points to be consider while choosing between the DataSet and DataReader objects

DataSet object	DataReader object
Read/Write access	Read-only access
Supports multiple tables from different databases	Supports a single table based on a single SQL query of one database
Disconnected mode	Connected mode
Bind to multiple controls	Bind to a single control
Forward and backward scanning of data	Forward-only scanning of data
Slower access to data	Faster access to data
Greater overhead to enable additional features	Lightweight object with very little overhead
Supported by Visual Studio .NET tools	Must be manually coded

Difference between catch(Exception ex) and catch

try
{
}
catch(Exception ex)
{
//Catches all cls-compliant exceptions
}
catch
{
//Catches all other exception including the non-cls compliant exceptions.
}

Maintain Scroll Position Rating Control Ajax

Ajax Rating Control has bug, that is whenever user clicks the rating control, page causes jumps to top of the page. To avoid jump to top of page when user clicks Rating Control you need to add following line.

Add following line to maintain scroll position of page after user clicks rating control asp.net ajax.


protected void Page_Load(object sender, EventArgs e)
{
Rating1.Attributes.Add("onclick", "return false;");
}

click Event Problem Firefox Solution

click Event in Firefox and Chrome doesn't work as expected, while it works perfectly with IE.I have a following Javascript code which was not working

document.getElementById('hlHome').click()

Where "hlHome" is ID of Home Link

Example: I have defined link like following

Following piece of code was working perfect with IE, but Firefox and Chrome didn't recognise this event.

Solution for Click Event Problem for Firefox, Chrome.

Wherever you are using click event as shown above replace that line with following.

window.location.href = document.getElementById('hlHome').href;

SQL Queries FAQ

T-SQL Queries
1. 2 tables
Employee Phone
empid
empname
salary
mgrid empid
phnumber

2. Select all employees who doesn't have phone?
SELECT empname
FROM Employee
WHERE (empid NOT IN
(SELECT DISTINCT empid
FROM phone))


3. Select the employee names who is having more than one phone numbers.
SELECT empname
FROM employee
WHERE (empid IN
(SELECT empid
FROM phone
GROUP BY empid
HAVING COUNT(empid) > 1))

4. Select the details of 3 max salaried employees from employee table.
SELECT TOP 3 empid, salary
FROM employee
ORDER BY salary DESC

5. Display all managers from the table. (manager id is same as emp id)
SELECT empname
FROM employee
WHERE (empid IN
(SELECT DISTINCT mgrid
FROM employee))

6. Write a Select statement to list the Employee Name, Manager Name
under a particular manager?
SELECT e1.empname AS EmpName, e2.empname AS ManagerName
FROM Employee e1 INNER JOIN
Employee e2 ON e1.mgrid = e2.empid
ORDER BY e2.mgrid

7. 2 tables emp and phone.
emp fields are - empid, name
Ph fields are - empid, ph (office, mobile, home). Select all employees
who doesn't have any ph nos.
SELECT *
FROM employee LEFT OUTER JOIN
phone ON employee.empid = phone.empid
WHERE (phone.office IS NULL OR phone.office = ' ')
AND (phone.mobile IS NULL OR phone.mobile = ' ')
AND (phone.home IS NULL OR phone.home = ' ')

8. Find employee who is living in more than one city.
Two Tables:
Emp City
Empid Empid
empName City
Salary
SELECT empname, fname, lname
FROM employee
WHERE (empid IN
(SELECT empid
FROM city
GROUP BY empid
HAVING COUNT(empid) > 1))

9. Find all employees who is living in the same city. (table is same
as above)
SELECT fname
FROM employee
WHERE (empid IN
(SELECT empid
FROM city a
WHERE city IN
(SELECT city
FROM city b
GROUP BY city
HAVING COUNT(city) > 1)))

10. There is a table named MovieTable with three columns - moviename,
person and role. Write a query which gets the movie details where Mr.

Amitabh and Mr. Vinod acted and their role is actor.
SELECT DISTINCT m1.moviename
FROM MovieTable m1 INNER JOIN
MovieTable m2 ON m1.moviename = m2.moviename
WHERE (m1.person = 'amitabh' AND m2.person = 'vinod' OR
m2.person = 'amitabh' AND m1.person = 'vinod') AND (m1.role = 'actor')
AND (m2.role = 'actor')
ORDER BY m1.moviename

11. There are two employee tables named emp1 and emp2. Both contains
same structure (salary details). But Emp2 salary details are incorrect
and emp1 salary details are correct. So, write a query which corrects
salary details of the table emp2
update a set a.sal=b.sal from emp1 a, emp2 b where a.empid=b.empid

12. Given a Table named "Students" which contains studentid, subjectid
and marks. Where there are 10 subjects and 50 students. Write a Query
to find out the Maximum marks obtained in each subject.

13. In this same tables now write a SQL Query to get the studentid
also to combine with previous results.

14. Three tables – student , course, marks – how do go @ finding name
of the students who got max marks in the diff courses.
SELECT student.name, course.name AS coursename, marks.sid, marks.mark
FROM marks INNER JOIN
student ON marks.sid = student.sid INNER JOIN
course ON marks.cid = course.cid
WHERE (marks.mark =
(SELECT MAX(Mark)
FROM Marks MaxMark
WHERE MaxMark.cID = Marks.cID))

15. There is a table day_temp which has three columns dayid, day and
temperature. How do I write a query to get the difference of
temperature among each other for seven days of a week?
SELECT a.dayid, a.dday, a.tempe, a.tempe - b.tempe AS Difference
FROM day_temp a INNER JOIN
day_temp b ON a.dayid = b.dayid + 1

OR
Select a.day, a.degree-b.degree from temperature a, temperature b
where a.id=b.id+1

16. There is a table which contains the names like this. a1, a2, a3,
a3, a4, a1, a1, a2 and their salaries. Write a query to get grand
total salary, and total salaries of individual employees in one query.
SELECT empid, SUM(salary) AS salary
FROM employee
GROUP BY empid WITH ROLLUP
ORDER BY empid

17. How to know how many tables contains empno as a column in a database?
SELECT COUNT(*) AS Counter
FROM syscolumns
WHERE (name = 'empno')

18. Find duplicate rows in a table? OR I have a table with one column
which has many records which are not distinct. I need to find the
distinct values from that column and number of times it's repeated.
SELECT sid, mark, COUNT(*) AS Counter
FROM marks
GROUP BY sid, mark
HAVING (COUNT(*) > 1)

19. How to delete the rows which are duplicate (don't delete both
duplicate records).
SET ROWCOUNT 1
DELETE yourtable
FROM yourtable a
WHERE (SELECT COUNT(*) FROM yourtable b WHERE b.name1 = a.name1 AND
b.age1 = a.age1) > 1
WHILE @@rowcount > 0
DELETE yourtable
FROM yourtable a
WHERE (SELECT COUNT(*) FROM yourtable b WHERE b.name1 = a.name1 AND
b.age1 = a.age1) > 1
SET ROWCOUNT 0

20. How to find 6th highest salary
SELECT TOP 1 salary
FROM (SELECT DISTINCT TOP 6 salary
FROM employee
ORDER BY salary DESC) a
ORDER BY salary

21. Find top salary among two tables
SELECT TOP 1 sal
FROM (SELECT MAX(sal) AS sal
FROM sal1
UNION
SELECT MAX(sal) AS sal
FROM sal2) a
ORDER BY sal DESC

22. Write a query to convert all the letters in a word to upper case
SELECT UPPER('test')

23. Write a query to round up the values of a number. For example even
if the user enters 7.1 it should be rounded up to 8.
SELECT CEILING (7.1)

24. Write a SQL Query to find first day of month?

SELECT DATENAME(dw, DATEADD(dd, - DATEPART(dd, GETDATE()) + 1,
GETDATE())) AS FirstDay
Datepart Abbreviations
year yy, yyyy
quarter qq, q
month mm, m
dayofyear dy, y
day dd, d
week wk, ww
weekday dw
hour hh
minute mi, n
second ss, s
millisecond ms

25. Table A contains column1 which is primary key and has 2 values (1,
2) and Table B contains column1 which is primary key and has 2 values
(2, 3). Write a query which returns the values that are not common for
the tables and the query should return one column with 2 records.
SELECT a.col1
FROM a, b
WHERE a.col1 <>
(SELECT b.col1
FROM a, b
WHERE a.col1 = b.col1)
UNION
SELECT b.col1
FROM a, b
WHERE b.col1 <>
(SELECT a.col1
FROM a, b
WHERE a.col1 = b.col1)

26. There are 3 tables Titles, Authors and Title-Authors. Write the
query to get the author name and the number of books written by that
author, the result should start from the author who has written the
maximum number of books and end with the author who has written the
minimum number of books.

27.
UPDATE emp_master
SET emp_sal =
CASE
WHEN emp_sal > 0 AND emp_sal <= 20000 THEN (emp_sal * 1.01) WHEN emp_sal > 20000 THEN (emp_sal * 1.02)
END