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SQL | Distinct Clause


The distinct keyword is used in conjunction with select keyword. It is helpful when there is need of avoiding the duplicate values present in any specific columns/table. When we use distinct keyword only the unique values are fetched.

Basic Syntax:

SELECT DISTINCT column1,column2 FROM table_name 
column1 , column2: names of the fields of the table
table_name: from where we want to fetch

This query will return all the unique combination of rows in the table with fields
column1 , column2. 

NOTE: If distinct keyword is used with multiple columns, the distinct combination is displayed in the result set.

table1

Queries



  • To fetch unique names from the NAME field
    SELECT DISTINCT NAME FROM Student;

    Output:

    NAME
    Ram
    RAMESH
    SUJIT
    SURESH
  • To fetch unique combination of rows from the whole table
    SELECT DISTINCT * FROM Student;

    Output:

    ROLL_NO NAME ADDRESS PHONE Age
    1 Ram Delhi XXXXXXXXXX 18
    2 RAMESH GURGAON XXXXXXXXXX 18
    3 SUJIT ROHTAK XXXXXXXXXX 20
    4 SURESH Delhi XXXXXXXXXX 18

    Please note: Without the keyword distinct in both the above examples 6 records would have been fetched instead of 4, since in the original table there are 6 records with the duplicate values.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.



This article is attributed to GeeksforGeeks.org

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