Friday, August 19, 2011

SQL Server interview questions: - How you can find the age of an Employee whose age is greater than 30?

This is one of the most typical questions asked in most of the interviews and is the favorable question of interviewers to check your skill on SQL.
Many of the developer fail to query this question and because of that they also
get rejected by the interviewers.

So, let’s demonstrate a simple example to see how exactly we can achieve the
above query in SQL.

Assume that we have the following table of Employee with their respective
fields, data types and data.

Now assuming the above table, we have to display the employee names whose age is
greater than 30.

In order to achieve the required result we have use SQL function called as “DATEDIFF”.

DATEDIFF: - Returns the count (signed integer) of the specified datepart
boundaries crossed between the specified startdate and enddate.

Syntax: -

DATEDIFF ( datepart , startdate , enddate )

Query: -

select Employees.EmployeeName, DATEDIFF(YEAR,EmployeeDOB,getdate())as Age

from Employees where DATEDIFF(YEAR,EmployeeDOB,getdate())>= 30
The above SQL query set will give output like below diagram.

Hence you can see that Employee names have been displayed whose age is greater
than 30.

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and tuning advisor

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