Changing column name
We make a table for storing some type of data. Table
keeps the data in the form of rows and columns. Column indicates the field while
row indicate the data of the field. Now consider a scenario where we have a
table and it consists some data and a situation arises where there is a need to
change the name of the column. As this is not the work of the programmer to
change the name of the field, but as a programmer we should be aware how we can
change the name of the column.
The name of the column of the column will be changed by
using the simple query. But before going into it we should see what are the
initial steps to get the desired results. First of all make a database
connection with your program. When the connection has been established pass a
query for changing the column name in the preparedStatement(). This will
return the PreparedStatement object.
The code of the program is given below:
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.sql.*;
public class ServletChangingColumnName extends HttpServlet{
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException{
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
String connectionURL = "jdbc:mysql://localhost/zulfiqar";
Connection connection;
try{
Class.forName("org.gjt.mm.mysql.Driver");
connection = DriverManager.getConnection(connectionURL, "root","admin");
PreparedStatement pst = connection.prepareStatement("alter table emp_details
change firstname Name varchar(10)");
int i = pst.executeUpdate();
pw.println("The name of the column has been changed");
}
catch(Exception e){
pw.println("The exception is " + e);
}
}
}
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web.xml file for this program:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<servlet>
<servlet-name>Zulfiqar</servlet-name>
<servlet-class>ServletChangingColumnName</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Zulfiqar</servlet-name>
<url-pattern>/ServletChangingColumnName</url-pattern>
</servlet-mapping>
</web-app>
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The table in the database before
changing of column name:
mysql> select * from emp_details;
+--------+----------+---------+-----------+----------+-------+-----------
| userId | Name | surname | address1 | address2 | town | country | zipcode
+--------+----------+---------+-----------+----------+-------+-----------
| 73979 | zulfiqar | Ahmed | Moradabad | Delhi | Okhla | India | 110025
+--------+----------+---------+-----------+----------+-------+-----------
1 row in set (0.00 sec) |
The output of the program is given below:
The table in the database after changing the
column name:
mysql> select * from
emp_details;
+--------+-----------+---------+-----------+----------+-------+-----------
| userId | firstname | surname | address1 | address2 | town | country | zipcode
+--------+-----------+---------+-----------+----------+-------+-----------
| 73979 | zulfiqar | Ahmed | Moradabad | Delhi | Okhla | India | 110025
+--------+-----------+---------+-----------+----------+-------+-----------
1 row in set (0.03 sec) |
Download this
program
|
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