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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Current Comments
1 comments so far (post your own) View All Comments Latest 10 Comments:tutor is good one can easily learn from this thanks and regards
Posted by jayasheel on Tuesday, 03.18.08 @ 16:46pm | #53180