Group By is used to group query results and perform aggregate functions, while Order By sorts the results without changing what is returned. Group By requires all non-aggregate columns in the select to be in the Group By clause, while Order By can sort on any columns. Group By execution occurs before Order By, and it can impact performance more than Order By due to the grouping of rows.

1. Difference between Group By and Order By in SQL Server
S.No Group By Order By
1 Meaning: Meaning:
Group By performs grouping Order By performs sorting operation
operation i.e., it provides a way to i.e., it provides a way to sort SQL
sub-total SQL Query results,or Query results like ascending or
perform some other aggregate descending . It does not affect what
functions (GROUPING SETS, shows up in the result set,only what
CUBE, ROLLUP, WITH CUBE, order it is displayed.
or WITH ROLLUP) on them.
2 Used for: Used for:
Controlling the presentation of the Controlling the presentation of the
rows for the results of the columns for the results of the
SELECT statement. SELECT statement.
3 Change in order of columns: Change in order of columns:
Order of columns make no Order of Columns makes difference in
difference in the GROUP BY ORDER BY Clause.
Clause.
For Example,
For Example,
ORDER BY A, B, C
GROUP BY A, B, C and
and ORDER BY C,A,B
GROUP BY C,A,B
Both returns the same number of
Both returns the same results. Records. But Row order will be
different.
4 Allowed in Create View Allowed in Create View Statement
Statement or not: or not:
GROUP BY clause can be used in ORDER BY clause is not allowed in
the CREATE VIEW statement to the CREATE VIEW statement.
sort data.
5 Execution Sequence: Execution Sequence:
The GROUP BY clause is always The ORDER BY clause is always
placed before the ORDER BY placed after the GROUP BY clause in
clause in the SELECT statement. the SELECT statement.
6 Impact on performance: Impact on performance:
As we know that Group By clubs As we now that Order By sorts the
all the similar rows and display data either in ascending order or in
only the distinct data. So here descending order as specified in the
clubbing and displaying distinct query. So here Sorting the data is an
data is an overhead. overhead.
Example-1 for Group By:

2. select * from employee group by emp_name.
this gives the output data in the group of the emp_name.
Example-2 for Group By:
SELECT department, sum(salary)
FROM tblEmployee
GROUP BY department;
will give us salary totals by department, whereas the sum statement by itself would just give us the
grand total of all salaries in tblEmployee.
Example-3 for Group By:
Group By helps us to display any aggregate of any column based on a field what has repeated
names.
use AdventureWorksDW2008R2
go
select Title,SUM(BaseRate) as Rate from dbo.DimEmployee group by Title
Title Rate
1 The Accountant 52.88
2 Accounts Manager 34.74
3 Accounts Payable Specialist 38
4 Accounts Receivable Specialist 57
5 Application Specialist 109.62
6 Assistant to the Chief Financial Officer 13.46
7 Benefits Specialist 16.59
8 Buyer 164.42
9 Chief Executive Officer 125.5
10 Chief Financial Officer 120.19
11 Control Specialist 33.65
12 Database Administrator 76.92
Example-1 for Order By:
select * from employee order by emp_name desc,emp_no asc;
this query gives the output in the ascending order of the emp_no and descending order of the
emp_name.
Example-2 for Order By:

3. SELECT *
FROM tblEmployee
ORDER BY lastname;
will give us all tblEmployee data, in order of last name. If we want the results in descending
(reversed) order, simply add DESC to the end of the clause: ORDER BY lastname DESC;
Example-3 for Order By:
Order By clause helps us to display any table based on the values present on that particular column.
use AdventureWorksDW2008R2
go
select FirstName,Title from dbo.DimEmployee order by FirstName
First Name Title
1 A. Scott The Master Scheduler
2 Alan Scheduling Assistant
3 Alejandro Production Technician - WC40
4 Alex Production Technician - WC45
5 Alice Production Technician - WC50
6 Amy European Sales Manager
7 Andreas Quality Assurance Technician
8 Andrew Production Supervisor -WC10
9 Andrew Production Technician - WC45
10 Andy Production Technician - WC30
11 Angela Production Technician - WC50
12 Anibal Production Technician - WC20
Summary:
1. All non-aggregate columns selected must be listed in the GROUP BY clause.
2. Integers cannot be used in the GROUP BY to represent columns after the SELECT keyword,
similar to using the ORDER BY clause.
3. The GROUP BY clause is generally not necessary unless using aggregate functions.
4. If we GROUP, the results are not necessarily sorted; although in many cases they may come
out in an intuitive order, that's not guaranteed by the GROUP clause. If we want our groups
sorted, always use an explicity ORDER BY after the GROUP BY. – Dave Costa
5. Processing of "group by" or "order by" clause often requires creation of Temporary tables to
process the results of the query. Which depending of the result set can be very expensive.
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