Tutorialspoint

1 Answer
Rishi Raj

The getColumnCount() method of the ResultSetMetaData (interface) retrieves the number of the columns of the current ResultSet object.

This method returns an integer value representing the number of columns.

To get the ResultSetMetaData object, you need to:

Register the Driver: Select the required database register the Driver class of the particular database using the registerDriver() method of the DriverManager class or, the forName() method of the class named Class.

DriverManager.registerDriver(new com.mysql.jdbc.Driver());

Get connection: Create a connection object by passing the URL of the database, username and password of a user in the database (in string format) as parameters to the getConnection() method of the DriverManager class.

Connection mysqlCon = DriverManager.getConnection(mysqlUrl, "root", "password");

Create a Statement object: Create a Statement object using the createStatement method of the connection interface.

Statement stmt = con.createStatement();

Execute the Query: Execute the SELECT query using the executeQuery() methods of the Statement interface and Retrieve the results into the ResultSet object.

String query = "Select * from MyPlayers";
ResultSet rs = stmt.executeQuery(query);

Get the ResultSetMetsdata object: Retrieve the ResultSetMetsdata object of the current ResultSet by invoking the getMetaData() method.

ResultSetMetaData resultSetMetaData = rs.getMetaData();

Finally, using the getColumnCount() method of the ResultSetMetaData interface get the number of columns in the table as:

int columnCount = resultSetMetaData.getColumnCount();

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 MySQL database, retrieves and displays the number of columns in the MyPlayers table using the getColumnCount() method.

Example

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
public class ResultSetMetaData_getColumnCount {
   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);
      //retrieving the ResultSetMetaData object
      ResultSetMetaData resultSetMetaData = rs.getMetaData();
      //Retrieving the column count of the current table
      int columnCount = resultSetMetaData.getColumnCount();
      System.out.println("Number of columns in the table represented by the current
         ResultSet object are: "+ columnCount);
   }
}

Output

Connection established......
Number of columns in the table represented by the current ResultSet object are: 6

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