I'm kind of a noob when it comes to SQL, so forgive me if this obvious.
I wanted to find duplicates of the Customer field, and the FULL records that had them.

**Note:** *I am using MS SQL Server 2005.*

I tried to implement the it as a single SQL Select statement before I came up with the following:

```
SELECT ModTab.* from modTab
    WHERE Customer IN (SELECT Customer
            FROM    ModTab
            GROUP BY Customer
            HAVING COUNT(Customer) > 1
        )
    ORDER BY Customer

```

Originally I tried a dozen differnt variations on something like:

```
SELECT ModTab.*
FROM    ModTab
GROUP BY Customer,<ALL other fields...>
HAVING COUNT(Customer) > 1

```

Is there something like the second approach which accomplishes the same thing?
(Plus the Group by clause seems someone pointless to me? I'm not realclear on why it's needed or used.)