Thursday, July 21, 2011

Distinct in SQL


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
2
11


Query 1:Select distinct PersonName from Orders
Query 2:Select distinct PersonName,Price from Orders


Query 1 : Even though price is different we used ‘distinct’ only on PersonName so it return only 4 records.
Query2 : Return 4 rows because Allen is repeated twice with same price so it returns Allen only Once

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