Check out example codes for "select where duplicate mysql". It will help you in understanding the concepts better.

Code Example 1

SELECT 
    col1, COUNT(col1),
    col2, COUNT(col2)
FROM
    table_name
GROUP BY 
    col1, 
    col2
HAVING 
       (COUNT(col1) > 1) AND 
       (COUNT(col2) > 1);

Code Example 2

SELECT name, COUNT(*) c FROM table GROUP BY name HAVING c > 1;

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