Java Database Connectivity (JDBC) is a Java API that allows developers to interact with relational databases. One of the key objects in JDBC is the ResultSet. In this blog, we’ll discuss what a ResultSet is, how to use it, and some of its important features.
What is a ResultSet
A ResultSet is an object that represents a table of data returned from a database query. It contains the rows of data that are retrieved from the database and can be used to iterate through the rows and access the data.
Using a ResultSet
To use a ResultSet, you first need to execute a query using a Statement or PreparedStatement object. The ResultSet object is then obtained by calling the executeQuery() method on the Statement or PreparedStatement object. The following code demonstrates this process:
Important Features of a ResultSet
- Cursor: The ResultSet object has a cursor that can be used to iterate through the rows in the ResultSet. The next() method is used to move the cursor to the next row in the ResultSet.
- Accessing Columns: The ResultSet provides various methods for accessing the columns in the ResultSet, such as getInt(), getString(), getDouble(), etc.
- Scrollability: The ResultSet can be scrollable or not. A scrollable ResultSet allows you to move the cursor to any row in the ResultSet, whereas a non-scrollable ResultSet only allows you to move the cursor forward through the ResultSet.
- Updatability: The ResultSet can be updatable or not. An updatable ResultSet allows you to modify the data in the ResultSet, whereas a non-updatable ResultSet does not allow you to modify the data.
- ResultSet Implementation: The ResultSet interface is implemented by the JDBC driver. The implementation details of the ResultSet are determined by the JDBC driver and can vary from driver to driver. However, all implementations of the ResultSet interface must provide the same basic functionality and must provide the same methods.
ResultSet to List
In this chapter we want to take a clooser look, how to get a List from a ResultSet.
Unfortunately you cannot just specify as return parameter list. Therefore you have to iterate through all elements in Resultset