In the above table, we can find duplicate row using below query.
SELECT name, section FROM tbl GROUP BY name, section HAVING COUNT(*) > 1
Given a table named PERSON task is to write an SQL query to find all duplicate name in the table.
+----+---------+ | Id | NAME | +----+---------+ | 1 | Geeks | | 2 | for | | 3 | Geeks | +----+---------+ Output : +---------+ | NAME | +---------+ | Geeks | +---------+
The simple approach is to make a temporary table which have count of all the names in a table.
Duplicated NAME existed more than one time, so to count the times each NAME exists, we can use the following code:
select NAME, count(NAME) as num from Person group by NAME;
| NAME | num | |---------|-----| | Geeks | 2 | | for | 1 |
This is a temporary table, on which we can run the below code to get duplicate NAME.
select NAME from ( select NAME, count(NAME) as num from Person group by NAME ) as statistic where num > 1;
The Best approach is to use GROUP BY and HAVING condition. It is more effective and faster then previous.
select NAME from Person group by NAME having count(NAME) > 1;
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