In this section, we are going to learn how to delete a column from a database table

Delete a Column from a Database Table

     

In this section, we are going to learn how to delete a column from a database table. We are not going to create a new table into, and we are expecting that you can make a table yourself. We are using the already created table in the specific database. Now if we want to delete a column from a database table then we have been provided with the  database query by which we can do this task very easily. See detailed information  below:

Description of program:

The thing which we are going to perform first is to establish the connection by using the JDBC driver. If any problem is created at the time of connection then it shows java.lang.ClassNotFoundException exception. After establishing the connection gives a table name and column name which you want to delete. When column gets deleted then it shows "Column is deleted successfully". But if SQL statement doesn't get executed then an exception is thrown and displays a message: "Table or column is not found!".

Description of code:

ALTER TABLE  table_name  DROP   col_name;
This code is used to delete the column form a database table 
  table_name: This is a table name in which you want to any editing.
  col_name: This is a column name which have to deleted.

Here is the code of program:

import java.io.*;
import java.sql.*;

public class DeleteColumn{
  public static void main(String[] args) {
  System.out.println("Delete columns example!");
  Connection con = null;
  try{
  Class.forName("com.mysql.jdbc.Driver");
  con = DriverManager.getConnection
("jdbc:mysql://localhost:3306/jdbctutorial","root","root");
  try{
  Statement st = con.createStatement();
  BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
  System.out.println("Enter table name: ");
  String table = bf.readLine();
  System.out.println("Enter column name: ");
  String col = bf.readLine();
  st.executeUpdate("ALTER TABLE "+table+" DROP "+col);
  System.out.println("Column is deleted successfully!");
  }
  catch (SQLException s){
  System.out.println("Table or column is not found!");
  }
  }
  catch (Exception e){
  e.printStackTrace();
  }
  }
} 

Database Table: Student Table

Stu_roll	Stu_name	Stu_sub	Stu_marks
100	vinod	computer	95
101	raju	math	89
102	ranjan	bio	80
103	Aman	phy	85

Output of program:

C:\vinod\jdbc\jdbc\jdbc-mysql>javac DeleteColumn.java C:\vinod\jdbc\jdbc\jdbc-mysql>java DeleteColumn Delete columns example! Enter table name: Student Enter column name: Stu_marks Column is deleted successfully!

After deleting a column: 

Student Table

Stu_roll	Stu_name	Stu_sub
100	vinod	computer
101	raju	math
102	ranjan	bio
103	Aman	phy

Download this example.

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