How to get the number of columns of a table using JDBC?

You can get the number of columns of a table using the getColumnCount() method of the ResultSetMetaData class.

//Retrieving the ResultSetMetaData object
ResultSetMetaData rsmd = rs.getMetaData();

//getting the column type
int column_count = rsmd.getColumnCount();

Assume we have a table named employee_data in the database with description as shown below:

+----------+--------------+------+-----+---------+-------+
| Field    | Type         | Null | Key | Default | Extra |
+----------+--------------+------+-----+---------+-------+
| id       | int(11)      | YES  |     | NULL    |       |
| Name     | varchar(255) | YES  |     | NULL    |       |
| Dob      | date         | YES  |     | NULL    |       |
| Location | varchar(255) | YES  |     | NULL    |       |
+----------+--------------+------+-----+---------+-------+

Following JDBC program establishes connection with the database, retrieves the ResultSetMetaData object of the employee_data table, and prints the number of columns in it.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class NumberOfColumns {
   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/mydatabase";
     Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
     System.out.println("Connection established......");

     //Creating a Statement object
     Statement stmt = con.createStatement();
     ResultSet rs = stmt.executeQuery("select * from employee_data");

     //Retrieving the ResultSetMetaData object
     ResultSetMetaData rsmd = rs.getMetaData();

     //getting the column type
     int column_count = rsmd.getColumnCount();
     System.out.println("Number of columns in the table : "+column_count);
   }
}

Output

Connection established......
Number of columns in the table : 4