SQL: Find duplicate values #mysql #sql #select #duplicate

duplicate.sql

SELECT 
    col, 
    COUNT(col)
FROM
    table_name
GROUP BY col
HAVING COUNT(col) > 1;

---

SELECT 
    col1, COUNT(col1),
    col2, COUNT(col2),
    ...

FROM
    table_name
GROUP BY 
    col1, 
    col2, ...
HAVING 
       (COUNT(col1) > 1) AND 
       (COUNT(col2) > 1) AND 
       ...
---

-- Get duplicates with column and row values
select s.id, t.* 
from [stuff] s
join (
    select name, city, count(*) as qty
    from [stuff]
    group by name, city
    having count(*) > 1
) t on s.name = t.name and s.city = t.city