ResultSet is basically useful for traversing through the data in the database.
ResultSet provides various getXXX methods to retrieve data from the database in various formats like int, double, String, Date, Timestamp etc.
A ResultSet maintains a cursor pointing to its current row of data. Initially the cursor is positioned before the first row. The 'next' method moves the cursor to the next row.
You can retrieve values using either the index number of the column. Columns are numbered from 1.
ResultSet's are two types.
1. Updateable
2. Non Updateable
The difference is Updateable ResultSet's allow you to update while traversing through the data while Non Updateable doen't.
You can find more in the following links :
ResultSet (Java 2 Platform SE v1.4.2)
Interface java.sql.ResultSet