Group By VS Distinct in SQL

Group by VS Distinct

Group By : The SQL GROUP BY statement is used together with the SQL aggregate functions to group the retrieved data by one or more columns. 

Distinct : The DISTINCT keyword can be used to return only distinct (different) values.

Orders table :

OrderId	PersonName	Price	Quantity
101	John	12	1
102	Sam	4	1
103	John	14	2
104	Brendon	12	1
106	Allen	2	11
107	Allen	3	11

Query 1: Select PersonName,Price from Orders group by PersonName,Price

Query 2:Select distinct PersonName,Price from Orders

Execution plan for both queries are same and return 5 records.

But the purpose of Group by is different it is used to group the records and apply aggregate function on it.

Query 3: Select PersonName,Sum(Price) as ‘Total’ from Orders group by PersonName

Query 3 returns only for records like below

PersonName	Total
Allen	5
Brendon	12
John	26
Sam	4