Usernames Chosen More Than Once
Problem
Table: `Signup`
```text
+-----------+---------+
| Column | Type |
+-----------+---------+
| signup_id | int |
| username | varchar |
+-----------+---------+
signup_id is the primary key. Each row is one signup attempt and the
username that was entered.
```
Write a query that lists every `username` that appears more than once in the table. Use the column heading `Username`.
Return the rows in any order.
**Example**
```text
Signup:
+-----------+----------+
| signup_id | username |
+-----------+----------+
| 1 | maple |
| 2 | cedar |
| 3 | maple |
+-----------+----------+
Output:
+----------+
| Username |
+----------+
| maple |
+----------+
```
`maple` was entered twice, so it appears in the result. `cedar` was entered only once, so it does not.
Tables
Example rows — the live problem includes the full dataset.
| signup_id | username |
|---|---|
| 1 | maple |
| 2 | cedar |
| 3 | maple |
Expected output
Your answer should return 1 row with the columns Username.
Starter code (SQL)
SELECT *
FROM Signup;Solve this SQL question free
Write SQL and run it instantly in your browser — even on your phone. No signup needed to try.
Solution & explanation
Create a free account to unlock the optimal solution, a step-by-step explanation, and the hidden test cases that grade your answer.
Sign up free to unlock