Problem
Write a SQL query to find all duplicate emails in a table named Person.
+----+---------+
| Id | Email |
+----+---------+
| 1 | a@b.com |
| 2 | c@d.com |
| 3 | a@b.com |
+----+---------+
For example, your query should return the following for the above table:
+---------+
| Email |
+---------+
| a@b.com |
+---------+
Note: All emails are in lowercase.
Solution 1
# Write your MySQL query statement below
select Email
from Person
group by Email
having count(Id) > 1
Explain:
nope.
Complexity:
- Time complexity :
- Space complexity :
Solution 2
# Write your MySQL query statement below
select
distinct a.Email as Email
from Person a, Person b
where a.Id <> b.Id
and a.Email = b.Email
Explain:
nope.
Complexity:
- Time complexity :
- Space complexity :