Finding Duplicates

[Sharon Lima]

Elementary relapse!   I know I had this at one time but today I cannot seem to find it or figure it out.  I need the command to select all rows from a table where the id# has been used in more than one row.   For example, I have 25000 rows of data and in a few cases an id# has been incorrectly used in more that one record.  This happened before a rule was in place but now I want to find the duplicated id#s so pre-existing data will not be in violation of the rule.   Thanks for help.   Sharon