I just start to learn MySQL, and I have a question regarding one specific query. I have a table called 'table1' as following :

[![enter image description here](https://i.stack.imgur.com/NH9Xi.jpg)](https://i.stack.imgur.com/NH9Xi.jpg)

I want to know if there are different rows with the same value of Gender, age, and postcode. In this case, the query should display :

[![enter image description here](https://i.stack.imgur.com/ZnZ9g.jpg)](https://i.stack.imgur.com/ZnZ9g.jpg)

For now, in order to solve this problem, I just use GROUP BY and check them manually:

```
 SELECT * FROM table1
 GROUP BY Gender, age, postcode

```

But for bigger data, it will be too hard to do check them manually.

Can anyone help me?

Thanks