Tutorialspoint

1 Answer
Arushi

When we execute certain SQL queries (SELECT query in general) they return tabular data.

The java.sql.ResultSet interface represents such tabular data returned by the SQL statements.

i.e. the ResultSet object holds the tabular data returned by the methods that execute the statements which quires the database (executeQuery() method of the Statement interface in general).

The ResultSet object has a cursor/pointer which points to the current row. Initially this cursor is positioned before first row.

The beforeFirst() method of the ResultSet interface moves the pointer of the current (ResultSet) object to the default position (before first), from the current position.

Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("Select * from MyPlayers");

Let us create a table with name MyPlayers in MySQL database using CREATE statement as shown below: 

CREATE TABLE MyPlayers(
   ID INT,
   First_Name VARCHAR(255),
   Last_Name VARCHAR(255),
   Date_Of_Birth date,
   Place_Of_Birth VARCHAR(255),
   Country VARCHAR(255),
   PRIMARY KEY (ID)
);

Now, we will insert 7 records in MyPlayers table using INSERT statements:

insert into MyPlayers values(1, 'Shikhar', 'Dhawan', DATE('1981-12-05'), 'Delhi', 'India');
insert into MyPlayers values(2, 'Jonathan', 'Trott', DATE('1981-04-22'), 'CapeTown', 'SouthAfrica');
insert into MyPlayers values(3, 'Kumara', 'Sangakkara', DATE('1977-10-27'), 'Matale', 'Srilanka');
insert into MyPlayers values(4, 'Virat', 'Kohli', DATE('1988-11-05'), 'Delhi', 'India');
insert into MyPlayers values(5, 'Rohit', 'Sharma', DATE('1987-04-30'), 'Nagpur', 'India');
insert into MyPlayers values(6, 'Ravindra', 'Jadeja', DATE('1988-12-06'), 'Nagpur', 'India');
insert into MyPlayers values(7, 'James', 'Anderson', DATE('1982-06-30'), 'Burnley', 'England');

Following JDBC program establishes connection with the database, retrieves the contents of the table MyPlayers into a ResultSet object, prints its contents, moves the cursor to the default position (before first row) and, prints the contents of the table again.

Example

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class ResultSet_beforeFirst {
   public static void main(String args[]) throws SQLException {
      //Registering the Driver
      DriverManager.registerDriver(new com.mysql.jdbc.Driver());
      //Getting the connection
      String mysqlUrl = "jdbc:mysql://localhost/mydatabase";
      Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
      System.out.println("Connection established......");
      //Creating the Statement
      Statement stmt = con.createStatement();
      //Query to retrieve records
      String query = "Select * from MyPlayers";
      //Executing the query
      ResultSet rs = stmt.executeQuery(query);
      System.out.println("Contents of the MyPlayers table: ");
      while(rs.next()) {
         System.out.print("ID: "+rs.getInt("ID")+", ");
         System.out.print("Name: "+rs.getString("First_Name")+", ");
         System.out.print("Age: "+rs.getString("Last_Name")+", ");
         System.out.print("Salary: "+rs.getDate("Date_Of_Birth")+", ");
         System.out.print("Country: "+rs.getString("Place_Of_Birth")+", ");
         System.out.print("Address: "+rs.getString("Country"));
         System.out.println();
      }
      System.out.println();
      //Moving cursor to the default position (before first row).
      rs.beforeFirst();
      System.out.println("Printing the contents of the table again");
      while(rs.next()) {
         System.out.print("ID: "+rs.getInt("ID")+", ");
         System.out.print("Name: "+rs.getString("First_Name")+", ");
         System.out.print("Age: "+rs.getString("Last_Name")+", ");
         System.out.print("Salary: "+rs.getDate("Date_Of_Birth")+", ");
         System.out.print("Country: "+rs.getString("Place_Of_Birth")+", ");
         System.out.print("Address: "+rs.getString("Country"));
         System.out.println();
      }
   }
}

Output

Connection established......
Contents of the MyPlayers table:
ID: 1, Name: Shikhar, Age: Dhawan, Salary: 1981-12-05, Country: Delhi, Address: India
ID: 2, Name: Jonathan, Age: Trott, Salary: 1981-04-22, Country: CapeTown, Address: SouthAfrica
ID: 3, Name: Kumara, Age: Sangakkara, Salary: 1977-10-27, Country: Matale, Address: Srilanka
ID: 4, Name: Virat, Age: Kohli, Salary: 1988-11-05, Country: Mumbai, Address: India
ID: 5, Name: Rohit, Age: Sharma, Salary: 1987-04-30, Country: Nagpur, Address: India
ID: 6, Name: Ravindra, Age: Jadeja, Salary: 1988-12-06, Country: Nagpur, Address: India
ID: 7, Name: James, Age: Anderson, Salary: 1982-06-30, Country: Burnley , Address: England
ID: 8, Name: Ryan, Age: McLaren, Salary: 1983-02-09, Country: Kumberly, Address: null
printing the contents of the table again
ID: 1, Name: Shikhar, Age: Dhawan, Salary: 1981-12-05, Country: Delhi, Address: India
ID: 2, Name: Jonathan, Age: Trott, Salary: 1981-04-22, Country: CapeTown, Address: SouthAfrica
ID: 3, Name: Kumara, Age: Sangakkara, Salary: 1977-10-27, Country: Matale, Address: Srilanka
ID: 4, Name: Virat, Age: Kohli, Salary: 1988-11-05, Country: Mumbai, Address: India
ID: 5, Name: Rohit, Age: Sharma, Salary: 1987-04-30, Country: Nagpur, Address: India
ID: 6, Name: Ravindra, Age: Jadeja, Salary: 1988-12-06, Country: Nagpur, Address: India
ID: 7, Name: James, Age: Anderson, Salary: 1982-06-30, Country: Burnley , Address: England
ID: 8, Name: Ryan, Age: McLaren, Salary: 1983-02-09, Country: Kumberly, Address: null

Advertisements

We use cookies to provide and improve our services. By using our site, you consent to our Cookies Policy.