Find Duplicate Records in SQL Oracle. SQL Server, or Access

Find Duplicate Records in SQL Oracle. SQL Server, or Access by Les Smith

How can I find duplicate records on a field in a database table?  This works in SQL Server, Oracle, or Access.

Quite often I encounter the need to find duplicate rcords in database tables.  This brief article will return a results set of duplicate records.
In order to find duplicate values in a table, use the following SQL.
SIMPLE:

select distinct employee from employees (nolock) group by employee having count(employee) > 1 order by employee

Complex:

select employee, firstname, lastname, dob from employees (nolock) where employee in (select employee from employees (nolock) group by employee having count(employee)>1) order by employee