A ResultSet interface in JDBC represents the tabular data generated by SQL queries. It has a cursor which points to the current row. Initially, this cursor is positioned before the first row.
Moving the pointer throughout result set
The next() method of the ResultSet interface moves the pointer of the current (ResultSet) object to the next row, from the current position. This method returns a boolean value, if there are no rows next to its current position it returns false, else it returns true. Therefore, using this method in the while loop you can iterate the contents of the result set.
while(rs.next()){
}Getting the column values of each record:
ResultSet interface (also) provides getter methods (getXXX()) to retrieve values in each column of a row. Every getter methods have two variants:
getXXX(int columnIndex): This accepts an integer value representing the index of the column and returns its value.
getXXX(String columnLabel ): This accepts a String value representing the name of the column and returns its value.
You need to use the respective getter method based on the datatype of the column in the table.
Example
Assume we have a table named dataset with content as shown below:
+--------------+-----------+ | mobile_brand | unit_sale | +--------------+-----------+ | Iphone | 3000 | | Samsung | 4000 | | Nokia | 5000 | | Vivo | 1500 | | Oppo | 900 | | MI | 6400 | | MotoG | 4360 | | Lenovo | 4100 | | RedMi | 4000 | | MotoG | 4360 | | OnePlus | 6334 | +--------------+-----------+
Example
The following example retrieves all the records of the Dataset table and prints the results:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class RetrievingData {
public static void main(String args[]) throws Exception {
//Registering the Driver
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//Getting the connection
String mysqlUrl = "jdbc:mysql://localhost/TestDB";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
//Creating a Statement object
Statement stmt = con.createStatement();
//Retrieving the data
ResultSet rs = stmt.executeQuery("select * from Dataset");
System.out.println("Contents of the table");
while(rs.next()) {
System.out.print("Brand: "+rs.getString("Mobile_Brand")+", ");
System.out.print("Sale: "+rs.getString("Unit_Sale"));
System.out.println("");
}
}
}Output
Connection established...... Contents of the table Brand: Iphone, Sale: 3000 Brand: Samsung, Sale: 4000 Brand: Nokia, Sale: 5000 Brand: Vivo, Sale: 1500 Brand: Oppo, Sale: 900 Brand: MI, Sale: 6400 Brand: MotoG, Sale: 4360 Brand: Lenovo, Sale: 4100 Brand: RedMi, Sale: 4000 Brand: MotoG, Sale: 4360 Brand: OnePlus, Sale: 6334