Java ResultSet isBeforeFirst() method with example


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 isBeforeFirst() method of the ResultSet interface is used to determine whether the cursor is at the default position of the ResultSet.

rs.isBeforeFirst();

This method returns an boolean this value is true, if the cursor is at the default position of the ResultSet else, it returns false.

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 and, determines whether the cursor is at the default position of the ResultSet.

Example

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class ResultSet_isBeforeFirst {
   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);
      //Verifying whether the cursor is at the end of the ResultSet (after last).
      boolean bool= rs.isBeforeFirst();
      if(bool) {
         System.out.println("Cursor of the current ResultSet object is at the default poition of the ResultSet");
      } else {
         System.out.println("Cursor of the current ResultSet object is not at the default poition of the ResultSet");
      }
      rs.beforeFirst();
      if(rs.isBeforeFirst()) {
         System.out.println("Cursor of the current ResultSet object is at the default poition of the ResultSet");
      } else {
         System.out.println("Cursor of the current ResultSet object is not at the default poition of the ResultSet");
      }
   }
}

Output

Connection established......
Cursor of the current ResultSet object is at the default poition of the ResultSet
Cursor of the current ResultSet object is at the default poition of the ResultSet
raja
Published on 15-May-2019 16:09:07
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