SQL > SQL Commands > Distinct

SQL > SQL Commands > Distinct

In SQL, the DISTINCT keyword is used in the SELECT statement to retrieve unique values from a database table. Any value that has a duplicate will only show up once.

SQL में, डेटाबेस तालिका से अद्वितीय मानों को पुनः प्राप्त करने के लिए चयन कथन में DISTINCT कीवर्ड का उपयोग किया जाता है। कोई भी मूल्य जिसमें एक डुप्लिकेट है वह केवल एक बार दिखाएगा।

Syntax

SELECT DISTINCT "column_name"
FROM "table_name";

"table_name" is the name of the table where data is stored, and "column_name" is the name of the column containing the data to be retrieved.

"table_name" उस तालिका का नाम है जहां डेटा संग्रहीत किया जाता है, और "column_name" उस स्तंभ का नाम है जिसमें डेटा पुनर्प्राप्त किया जाना है।

Examples

The examples will use the following table:

Table Store_Information

Store_Name	Sales	Txn_Date
Los Angeles	1500	Jan-05-1999
San Diego	250	Jan-07-1999
Los Angeles	300	Jan-08-1999
Boston	700	Jan-08-1999

Example 1: Use DISTINCT on one column

To select all distinct stores in Table Store_Information, we key in,

SELECT DISTINCT Store_Name FROM Store_Information;

Result:

Store_Name
Los Angeles
San Diego
Boston

Example 2: Use DISTINCT on multiple columns

We can apply DISTINCT to multiple columns. If we want to get a list showing all unique combinations of stores and transaction dates, we would type in the following,

हम कई कॉलम में DISTINCT लगा सकते हैं। यदि हम स्टोर और लेन-देन की तारीखों के सभी विशिष्ट संयोजनों को दर्शाने वाली एक सूची प्राप्त करना चाहते हैं, तो हम निम्नलिखित में टाइप करेंगे,

SELECT DISTINCT Store_Name, Txn_Date FROM Store_Information;

Result:

Store_Name	Txn_Date
Los Angeles	Jan-05-1999
San Diego	Jan-07-1999
Los Angeles	Jan-08-1999
Boston	Jan-08-1999

Exercises

For these exercises, assume we have a table called Users with the following data:

Table Users

First_Name	Last_Name	Birth_Date	Gender	Join_Date
Sophie	Lee	Jan-05-1960	F	Apr-05-2015
Richard	Brown	Jan-07-1975	M	Apr-05-2015
Jamal	Santo	Oct-08-1983	M	Apr-09-2015
Casey	Healy	Sep-20-1969	M	Apr-09-2015
Jill	Wilkes	Nov-20-1979	F	Apr-15-2015

1. Which of the following SQL statement is valid?
a) SELECT DISTINCT * FROM Users;
b) SELECT DISTINCT First_Name FROM Users;
c) SELECT DISTINCT First_Name Last_Name FROM Users;

2. What's the result of the following query?
SELECT DISTINCT Join_Date From Users;

3. What's the result of the following query?
SELECT DISTINCT Gender, Join_Date From Users;

1. b)
2. The result is:

Join_Date

Apr-05-2015

Apr-09-2015

Apr-15-2015

3. The result is:

Gender	Join_Date
F	Apr-05-2015
M	Apr-05-2015
M	Apr-09-2015
F	Apr-15-2015