MySQL में डुप्लीकेट रिकॉर्ड कैसे खोजें और दिखाएं?

GROUP BY ... HAVING COUNT(*) > 1 से डुप्लीकेट वाली रो खोजें।

उदाहरण

CREATE TABLE DuplicateFound (ID INT, Name VARCHAR(100), Location VARCHAR(200));
INSERT INTO DuplicateFound VALUES
(1,'John','US'), (2,'Bob','UK'), (3,'David','US'),
(4,'Smith','US'), (5,'Carol','UK');

डुप्लीकेट लोकेशन वाली सभी रो

SELECT * FROM DuplicateFound
WHERE Location IN (
    SELECT Location FROM DuplicateFound
    GROUP BY Location HAVING COUNT(Location) > 1
)
ORDER BY Location;

आउटपुट

+------+-------+----------+
| ID   | Name  | Location |
+------+-------+----------+
| 2    | Bob   | UK       |
| 5    | Carol | UK       |
| 1    | John  | US       |
| 3    | David | US       |
| 4    | Smith | US       |
+------+-------+----------+

सिर्फ डुप्लीकेट ग्रुप दिखाएं

SELECT Name, Location FROM DuplicateFound
GROUP BY Location HAVING COUNT(Location) > 1;