Group By and Where Clause

 Group by and where clause are used for Fetch the data with filtering.Firstly Where execute and after that Group By Clause.

WHERE: The WHERE clause is executed to filter out records that do not meet the constraints and The GROUP BY clause is executed to group the data based on the values in one or more columns.

Hello Deepak.

Let me give you an example for your question... Suppose we have a table something like this...

Table Name: Employee
Columns:
Emp_ID         Emp_Name            Emp_City
01                Deepak                Mumbai
02                Shiv                    Delhi
03                Ramesh                Mumbai
04                Satyapriya            Kolkata

1) Where Clause: Suppose you want the result of employee staying in Delhi. So in that case you will use a where clause to put a condition in your query to get the desired result. You will write it this way.

"Select * from Employee where Emp_City = 'Delhi'"
This will give you the following result.
Result:
Emp_ID         Emp_Name            Emp_City
02                Shiv                    Delhi

2) Group By Clause: Suppose you want an aggregate result of the employees who stay only in Mumbai, then you can use the Group By Clause.

"Select Count(Emp_ID) as Total Employees , Emp_City from Employee Group By Emp_City"
This will give you the following result.
Result:
Total Employees        Emp_City
1                                Delhi
1                                Kolkata
2                                Mumbai

Please check out these links to know more about Group By and Where Clause.
For Group By Clause
http://www.techonthenet.com/sql/group_by.php 

http://weblogs.sqlteam.com/jeffs/archive/2005/12/14/8546.aspx 

http://www.1keydata.com/sql/sqlgroupby.html 

For Where Clause
http://www.1keydata.com/sql/sqlwhere.html

Hope this will help you... 
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THANK YOU!!!

Group by- is applicable to grouping of all the records in a table.

WHere- It will check the condition or matches with individual rows.

Group by and Having- When we use having together with group by it will fetch group of records satisfying conditions