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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
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