Check out example codes for "DISTINCT SQL". It will help you in understanding the concepts better.

Code Example 1

SELECT DISTINCT column1, column2, ...

 FROM table_name;

Code Example 2

SELECT DISTINCT column1, column1, ..... FROM TABLE
/*DISTINCT WILL NOT SELECT THE SAME VALUES IN SAME COLUMN*/

Code Example 3

SELECT DISTINCT Column_name FROM table_name;

Code Example 4

SELECT DISTINCT ma_colonne
FROM nom_du_tableau

Code Example 5

SELECT a.*
FROM emails a
INNER JOIN 
  (SELECT email,
    MIN(id) as id
  FROM emails 
  GROUP BY email 
) AS b
  ON a.email = b.email 
  AND a.id = b.id;

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