Monday, May 24, 2010

Sum of Column in a Database Table

This section describes how we can calculate the sum of specific column data in the database table. Consider an example of any university where we need to calculate the sum of numbers achieved by the student. Either we can do it manually or by using just the simple query. By doing it manually is a very cumbersome work, but by using simple query it can be done very easily. By seeing the example given below you can easily understand how you can get the sum of specific column. Here we are providing you an example.

Description of program:

In the program the first task we going to do is to establish the connection with MySQL database by using the JDBC driver. When the connection has been established pass the table name and name of that column of which we want to calculate the sum. If the statement gets processed then it shows the sum of the particular column else it will displays a message "SQL statement is not executed!".

Description of code:

SELECT SUM(col_name) FROM table_name:
This code can be used to calculate the sum of specific column in database table.

Here is the code of program:

import java.io.*;
import java.sql.*;

public class SumColumn{
public static void main(String[] args) {
System.out.println("Sum of the specific column!");
Connection con = null;
int sum = 0;
String col_name;
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 which have to sum:");
String col = bf.readLine();
ResultSet res = st.executeQuery("SELECT SUM"+"("+col+")"+" FROM "+table);
while (res.next()){
int c = res.getInt(1);
sum = sum+c;
}
System.out.println("Sum of column = "+sum);
}
catch (SQLException s){
System.out.println("SQL statement is not executed!");
}
}
catch (Exception e){
e.printStackTrace();
}
}
}
Download this example.

Output of program:

C:\vinod\jdbc\jdbc\jdbc-mysql>javac SumColumn.java

C:\vinod\jdbc\jdbc\jdbc-mysql>java SumColumn
Sum of the specific column!
Enter table name:
emp_sal
Enter column name which have to sum:
Emp_sal
Sum of column = 28100

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