I was looking for duplicates in my table and grouped the rows by my datetime column. I thought this would only find rows that had the exact same date and time, down to the second. However, I learned this was not the case. It found duplicates for just the date. Here is what I used:
select dateAdded, uID, type, subject, message, count(*) as total from notifications group by uID, type, subject, message having total > 1 order by type;
How come this works fine and yet an unique index on the dateAdded column will only prevent duplicate inserts if the date and time are exact, down to the second?