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.

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