SQL query to find employees hired in last n months

This question is asked is many sql server interviews. If you have used DATEDIFF() sql server function then you already know the answer. 

We will be using the following Employees table for this demo.


SQL Script to create the table and populate with test data

Create table Employees

(

     ID int primary key identity,

     FirstName nvarchar(50),

     LastName nvarchar(50),

     Gender nvarchar(50),

     Salary int,

     HireDate DateTime

)

GO

Insert into Employees values('Mark','Hastings','Male',60000,'5/10/2014')

Insert into Employees values('Steve','Pound','Male',45000,'4/20/2014')

Insert into Employees values('Ben','Hoskins','Male',70000,'4/5/2014')

Insert into Employees values('Philip','Hastings','Male',45000,'3/11/2014')

Insert into Employees values('Mary','Lambeth','Female',30000,'3/10/2014')

Insert into Employees values('Valarie','Vikings','Female',35000,'2/9/2014')

Insert into Employees values('John','Stanmore','Male',80000,'2/22/2014')

Insert into Employees values('Able','Edward','Male',5000,'1/22/2014')

Insert into Employees values('Emma','Nan','Female',5000,'1/14/2014')

Insert into Employees values('Jd','Nosin','Male',6000,'1/10/2013')

Insert into Employees values('Todd','Heir','Male',7000,'2/14/2013')

Insert into Employees values('San','Hughes','Male',7000,'3/15/2013')

Insert into Employees values('Nico','Night','Male',6500,'4/19/2013')

Insert into Employees values('Martin','Jany','Male',5500,'5/23/2013')

Insert into Employees values('Mathew','Mann','Male',4500,'6/23/2013')

Insert into Employees values('Baker','Barn','Male',3500,'7/23/2013')

Insert into Employees values('Mosin','Barn','Male',8500,'8/21/2013')

Insert into Employees values('Rachel','Aril','Female',6500,'9/14/2013')

Insert into Employees values('Pameela','Son','Female',4500,'10/14/2013')

Insert into Employees values('Thomas','Cook','Male',3500,'11/14/2013')

Insert into Employees values('Malik','Md','Male',6500,'12/14/2013')

Insert into Employees values('Josh','Anderson','Male',4900,'5/1/2014')

Insert into Employees values('Geek','Ging','Male',2600,'4/1/2014')

Insert into Employees values('Sony','Sony','Male',2900,'4/30/2014')

Insert into Employees values('Aziz','Sk','Male',3800,'3/1/2014')

Insert into Employees values('Amit','Naru','Male',3100,'3/31/2014')

Here is the SQL Query that does the job

-- Replace N with number of months

Select *

FROM Employees

Where DATEDIFF(MONTH, HireDate, GETDATE()) Between 1 and N